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CVE-2026-8927

CRITICAL 9.1 ALL-YEARS

Published 2026-07-03 · Last modified 2026-09-15 · curl · NVD: Modified

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against `proxyA` using Digest auth, a subsequent transfer routed through `proxyB` erroneously leaks the `Proxy-Authorization:` header intended solely for `proxyA`.

ELEVATED IMPACT

Severe if exploited (CVSS 9.1), but no confirmed exploitation. Patch on a normal cadence.

Exploitation likelihood

0.5%chance of exploitation in 30 days · 43rd percentile

○ In CISA KEV○ Catalogued PoC◆ SSVC: exploitation poc, automatable no

Impact if exploited

9.1CVSS 3.1 · CRITICAL · ADP

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityNone

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

Search for new PoCs

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Tracked sources are checked weekly for the full archive, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Data snapshot:

Affected

Vendors Curl Haxx

Products Curl

Weakness (CWE)

  • CWE-294: Authentication Bypass by Capture-replay

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References and research data (JSON)

Vendor product assessments

Showing 32 of 395 vendor product statements; 363 omitted. Read the full vendor advisory.

  • curl-debuginfo-0:8.12.1-1.el10_0.10.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0) · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]_0.10?arch=aarch64

    • vendor fix: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • curl-debugsource-0:8.12.1-4.el10_2.4.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10) · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]_2.4?arch=s390x

    • vendor fix: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • curl-minimal-debuginfo-0:7.76.1-40.el9_8.7.i686 as a component of Red Hat Enterprise Linux AppStream (v. 9) · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]_8.7?arch=i686

    • vendor fix: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • curl-debuginfo-0:8.12.1-1.el10_0.10.s390x as a component of Red Hat Enterprise Linux BaseOS EUS (v. 10.0) · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]_0.10?arch=s390x

    • vendor fix: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • curl-0:8.12.1-4.el10_2.4.x86_64 as a component of Red Hat Enterprise Linux BaseOS (v. 10) · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]_2.4?arch=x86_64

    • vendor fix: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • curl-0:7.76.1-40.el9_8.7.aarch64 as a component of Red Hat Enterprise Linux BaseOS (v. 9) · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]_8.7?arch=aarch64

    • vendor fix: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • libcurl-0:7.76.1-40.el9_8.7.ppc64le as a component of Red Hat Enterprise Linux BaseOS (v. 9) · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]_8.7?arch=ppc64le

    • vendor fix: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • registry.redhat.io/cert-manager/cert-manager-operator-rhel9@sha256:0bfd185a474fc2a5adf322c153f804799f38e0cb190528ff0b9be9c101c3eaca_s390x as a component of Cert Manager support for Red Hat OpenShift release 1.20 · fixed

    Vendor assessment for this product only.

    pkg:oci/cert-manager-operator-rhel9@sha256%3A0bfd185a474fc2a5adf322c153f804799f38e0cb190528ff0b9be9c101c3eaca?arch=s390x&repository_url=registry.redhat.io/cert-manager/cert-manager-operator-rhel9&tag=1790272426

    • vendor fix: Before applying this update, make sure all previously released errata relevant to your system have been applied. The steps to apply the upgraded images are different depending on the installation plan approval policy you used when installing the cert-manager Operator for Red Hat OpenShift. - If the approval policy is set to `Automatic`, then the Operator will be upgraded automatically when there is a new version of the Operator. No further action is required to upgrade. This is the default setting. - If you changed the approval policy to `Manual`, then you must manually approve the upgrade to the Operator. See https://docs.openshift.com/container-platform/latest/security/cert_manager_operator/index.html for additional information. Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • curl-0:8.21.0-0.1.hum1@x86_64 as a component of Red Hat Hardened Images · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]?arch=x86_64&distro=hummingbird-20251124&repository_id=public-hummingbird-x86_64-rpms

    • vendor fix: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/ Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • rust-std-static-aarch64-unknown-none-softfloat-0:1.96.1-1.hum1@noarch@public-hummingbird-x86_64-rpms as a component of Red Hat Hardened Images · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]?arch=noarch&distro=hummingbird-20251124&repository_id=public-hummingbird-x86_64-rpms

    • vendor fix: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/ Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • registry.redhat.io/rhui5/rhua-rhel9@sha256:d20d237b12a31033a78d5a4dccf3ba61cfa43cdb564993c98997e6813d20cfd8_amd64 as a component of Red Hat Update Infrastructure 5 · fixed

    Vendor assessment for this product only.

    pkg:oci/rhua-rhel9@sha256%3Ad20d237b12a31033a78d5a4dccf3ba61cfa43cdb564993c98997e6813d20cfd8?arch=amd64&repository_url=registry.redhat.io/rhui5/rhua-rhel9&tag=1790242004

    • vendor fix: The container images provided by this release, apart from the installer, should be deployed using rhui-installer utility. See the official documentation for more details. Vendor guidance
    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • build-of-trustee/trustee-rhel9 as a component of Confidential Compute Attestation · known affected

    Vendor assessment for this product only.

    pkg:oci/trustee-rhel9?repository_url=registry.redhat.io/build-of-trustee/trustee-rhel9

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • none available: Affected
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • snphost.src as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/snphost?arch=src

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • none available: Affected
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • curl.src as a component of Red Hat Enterprise Linux 6 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/curl?arch=src

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • no fix planned: Will not fix
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • libcurl-devel as a component of Red Hat Enterprise Linux 6 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/libcurl-devel

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • no fix planned: Will not fix
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • curl.src as a component of Red Hat Enterprise Linux 7 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/curl?arch=src

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • none available: Affected
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • libcurl-devel as a component of Red Hat Enterprise Linux 7 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/libcurl-devel

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • none available: Affected
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • curl.src as a component of Red Hat Enterprise Linux 8 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/curl?arch=src

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • none available: Affected
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • libcurl-devel as a component of Red Hat Enterprise Linux 8 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/libcurl-devel

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • none available: Affected
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • snphost.src as a component of Red Hat Enterprise Linux 9 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/snphost?arch=src

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • none available: Affected
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • libcurl.so as a component of Red Hat JBoss Core Services · known affected

    Vendor assessment for this product only.

    pkg:generic/libcurl.so

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • no fix planned: Will not fix
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4 · known affected

    Vendor assessment for this product only.

    pkg:oci/ose-rhel-coreos-9?repository_url=registry.redhat.io/openshift/ose-rhel-coreos-9

    • workaround: To mitigate this issue, applications utilizing libcurl should avoid reusing handles when switching between different proxy configurations. This operational control prevents the unintended leakage of `Proxy-Authorization` headers to incorrect proxies.
    • none available: Affected
    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • registry.redhat.io/cert-manager/jetstack-cert-manager-acmesolver-rhel9@sha256:a5f4c1a5cffdd4a0449fdf9b05815810e92d27601e9d683ed647ee1c2e5df4cf_ppc64le as a component of Cert Manager support for Red Hat OpenShift release 1.20 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/jetstack-cert-manager-acmesolver-rhel9@sha256%3Aa5f4c1a5cffdd4a0449fdf9b05815810e92d27601e9d683ed647ee1c2e5df4cf?arch=ppc64le&repository_url=registry.redhat.io/cert-manager/jetstack-cert-manager-acmesolver-rhel9&tag=1790223630

    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • registry.redhat.io/devspaces/dashboard-rhel9@sha256:6b9d8089f76b0ba4008847692f2713a33949ef4774af43730d08b4b954dc317b_s390x as a component of Red Hat OpenShift Dev Spaces 3.30 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/dashboard-rhel9@sha256%3A6b9d8089f76b0ba4008847692f2713a33949ef4774af43730d08b4b954dc317b?arch=s390x&repository_url=registry.redhat.io/devspaces/dashboard-rhel9&tag=1790617428

    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • registry.redhat.io/devspaces/jetbrains-ide-rhel9@sha256:5edc00d72eb88b715d4240c76ced68cab413927727cfe5cb3e45554bf8530161_amd64 as a component of Red Hat OpenShift Dev Spaces 3.30 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/jetbrains-ide-rhel9@sha256%3A5edc00d72eb88b715d4240c76ced68cab413927727cfe5cb3e45554bf8530161?arch=amd64&repository_url=registry.redhat.io/devspaces/jetbrains-ide-rhel9&tag=1790616266

    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • registry.redhat.io/devspaces/openvsx-rhel9@sha256:7943be44109063a0d79a12eaef3520c048fcbc44f58fa47e692dec8ca4d88182_arm64 as a component of Red Hat OpenShift Dev Spaces 3.30 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/openvsx-rhel9@sha256%3A7943be44109063a0d79a12eaef3520c048fcbc44f58fa47e692dec8ca4d88182?arch=arm64&repository_url=registry.redhat.io/devspaces/openvsx-rhel9&tag=1790616590

    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • registry.redhat.io/devspaces/traefik-rhel9@sha256:96673c650389efc3309c67ef909b92050190e47e821c7f4eb5d1a23cc6045161_arm64 as a component of Red Hat OpenShift Dev Spaces 3.30 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/traefik-rhel9@sha256%3A96673c650389efc3309c67ef909b92050190e47e821c7f4eb5d1a23cc6045161?arch=arm64&repository_url=registry.redhat.io/devspaces/traefik-rhel9&tag=1790615456

    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • rust as a component of Red Hat Enterprise Linux 10 · known not affected

    Vendor assessment for this product only.

    Reason: component not present

    pkg:rpm/redhat/rust

    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • rust-toolset-srpm-macros as a component of Red Hat Enterprise Linux 10 · known not affected

    Vendor assessment for this product only.

    Reason: component not present

    pkg:rpm/redhat/rust-toolset-srpm-macros

    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • s390utils-mon_statd as a component of Red Hat Enterprise Linux 10 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/s390utils-mon_statd

    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • rust-debugger-common as a component of Red Hat Enterprise Linux 9 · known not affected

    Vendor assessment for this product only.

    Reason: component not present

    pkg:rpm/redhat/rust-debugger-common

    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00
  • rhtpa/rhtpa-trustification-service-rhel9 as a component of Red Hat Trusted Profile Analyzer · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:oci/rhtpa-trustification-service-rhel9?repository_url=registry.redhat.io/rhtpa/rhtpa-trustification-service-rhel9

    Red Hat · CVE-2026-8927 · Updated 2026-10-20T18:14:54+00:00

Known Affected Software Configurations

VendorProductVersion range
HaxxCurl≥ 7.12.0 and < 8.21.0

All CVSS metrics

  • CRITICAL 9.1 v3.1 · ADP Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
  • CRITICAL 9.1 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References

Exploit-tagged references (not proof of a PoC)

Patches & mitigations

Advisories

Technical & other

Sources: NVD · CVE.org · All sources and attribution · EPSS