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CVE-2026-69186

MEDIUM 5.3

Published 2026-09-18 · Last modified 2026-09-18

c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and release cycles that can degrade or deny name resolution, without causing memory corruption or information disclosure. This issue is fixed in version 1.34.7.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.5%chance of exploitation in 30 days · 40th percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

5.3CVSS 3.1 · MEDIUM

  • ConfidentialityNone
  • IntegrityNone
  • AvailabilityLow

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

Search GitHub now — results may be empty or unverified.

Tracked sources are checked daily for recent CVEs, 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 C Ares

Products C Ares

Weakness (CWE)

  • CWE-400: : Uncontrolled Resource Consumption

CVSS vector

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

References and research data (JSON)

Vendor product assessments

Showing 32 of 76 vendor product statements; 44 omitted. Read the full vendor advisory.

  • c-ares-0:1.34.8-2.hum1@aarch64 as a component of Red Hat Hardened Images · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]?arch=aarch64&distro=hummingbird-20251124&repository_id=public-hummingbird-aarch64-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: Configure applications that use c-ares to query only trusted DNS resolvers over a trusted network path (CME-202 host firewall; CME-203 network segmentation). Restrict DNS responses from untrusted sources so a malicious or on-path resolver cannot deliver crafted replies. There is no complete library-level workaround; apply a fixed c-ares update when available.
    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares-0:1.34.8-2.hum1@src as a component of Red Hat Hardened Images · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]?arch=src&distro=hummingbird-20251124&repository_id=public-hummingbird-source-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: Configure applications that use c-ares to query only trusted DNS resolvers over a trusted network path (CME-202 host firewall; CME-203 network segmentation). Restrict DNS responses from untrusted sources so a malicious or on-path resolver cannot deliver crafted replies. There is no complete library-level workaround; apply a fixed c-ares update when available.
    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares-0:1.34.8-2.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: Configure applications that use c-ares to query only trusted DNS resolvers over a trusted network path (CME-202 host firewall; CME-203 network segmentation). Restrict DNS responses from untrusted sources so a malicious or on-path resolver cannot deliver crafted replies. There is no complete library-level workaround; apply a fixed c-ares update when available.
    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares-devel-0:1.34.8-2.hum1@aarch64 as a component of Red Hat Hardened Images · fixed

    Vendor assessment for this product only.

    pkg:rpm/redhat/[email protected]?arch=aarch64&distro=hummingbird-20251124&repository_id=public-hummingbird-aarch64-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: Configure applications that use c-ares to query only trusted DNS resolvers over a trusted network path (CME-202 host firewall; CME-203 network segmentation). Restrict DNS responses from untrusted sources so a malicious or on-path resolver cannot deliver crafted replies. There is no complete library-level workaround; apply a fixed c-ares update when available.
    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares-devel-0:1.34.8-2.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: Configure applications that use c-ares to query only trusted DNS resolvers over a trusted network path (CME-202 host firewall; CME-203 network segmentation). Restrict DNS responses from untrusted sources so a malicious or on-path resolver cannot deliver crafted replies. There is no complete library-level workaround; apply a fixed c-ares update when available.
    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/c-ares

    • workaround: Configure applications that use c-ares to query only trusted DNS resolvers over a trusted network path (CME-202 host firewall; CME-203 network segmentation). Restrict DNS responses from untrusted sources so a malicious or on-path resolver cannot deliver crafted replies. There is no complete library-level workaround; apply a fixed c-ares update when available.
    • none available: Affected
    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares-devel as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/c-ares-devel

    • workaround: Configure applications that use c-ares to query only trusted DNS resolvers over a trusted network path (CME-202 host firewall; CME-203 network segmentation). Restrict DNS responses from untrusted sources so a malicious or on-path resolver cannot deliver crafted replies. There is no complete library-level workaround; apply a fixed c-ares update when available.
    • none available: Affected
    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares.src as a component of Red Hat Enterprise Linux 10 · known affected

    Vendor assessment for this product only.

    pkg:rpm/redhat/c-ares?arch=src

    • workaround: Configure applications that use c-ares to query only trusted DNS resolvers over a trusted network path (CME-202 host firewall; CME-203 network segmentation). Restrict DNS responses from untrusted sources so a malicious or on-path resolver cannot deliver crafted replies. There is no complete library-level workaround; apply a fixed c-ares update when available.
    • none available: Affected
    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • openshift/ose-rhel-coreos-8 as a component of Red Hat OpenShift Container Platform 4 · known affected

    Vendor assessment for this product only.

    pkg:oci/ose-rhel-coreos-8?repository_url=registry.redhat.io/openshift/ose-rhel-coreos-8

    • workaround: Configure applications that use c-ares to query only trusted DNS resolvers over a trusted network path (CME-202 host firewall; CME-203 network segmentation). Restrict DNS responses from untrusted sources so a malicious or on-path resolver cannot deliver crafted replies. There is no complete library-level workaround; apply a fixed c-ares update when available.
    • none available: Affected
    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+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: Configure applications that use c-ares to query only trusted DNS resolvers over a trusted network path (CME-202 host firewall; CME-203 network segmentation). Restrict DNS responses from untrusted sources so a malicious or on-path resolver cannot deliver crafted replies. There is no complete library-level workaround; apply a fixed c-ares update when available.
    • none available: Affected
    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs 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/nodejs

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs-full-i18n 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/nodejs-full-i18n

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares-devel as a component of Red Hat Enterprise Linux 6 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/c-ares-devel

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares-devel as a component of Red Hat Enterprise Linux 7 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/c-ares-devel

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares-devel as a component of Red Hat Enterprise Linux 8 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/c-ares-devel

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs-docs (nodejs:22) as a component of Red Hat Enterprise Linux 8 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs-docs?rpmmod=nodejs:22

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs-full-i18n (nodejs:24) as a component of Red Hat Enterprise Linux 8 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs-full-i18n?rpmmod=nodejs:24

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs-nodemon.src (nodejs:22) as a component of Red Hat Enterprise Linux 8 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs-nodemon?arch=src&rpmmod=nodejs:22

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs-packaging-bundler (nodejs:22) as a component of Red Hat Enterprise Linux 8 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs-packaging-bundler?rpmmod=nodejs:22

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs-packaging.src (nodejs:24) as a component of Red Hat Enterprise Linux 8 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs-packaging?arch=src&rpmmod=nodejs:24

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs.src (nodejs:22) as a component of Red Hat Enterprise Linux 8 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs?arch=src&rpmmod=nodejs:22

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs (nodejs:24) as a component of Red Hat Enterprise Linux 8 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs?rpmmod=nodejs:24

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • v8-12.4-devel (nodejs:24) as a component of Red Hat Enterprise Linux 8 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/v8-12.4-devel?rpmmod=nodejs:24

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • c-ares as a component of Red Hat Enterprise Linux 9 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/c-ares

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs-docs (nodejs:22) as a component of Red Hat Enterprise Linux 9 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs-docs?rpmmod=nodejs:22

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs-full-i18n (nodejs:24) as a component of Red Hat Enterprise Linux 9 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs-full-i18n?rpmmod=nodejs:24

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs-libs (nodejs:24) as a component of Red Hat Enterprise Linux 9 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs-libs?rpmmod=nodejs:24

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs.src (nodejs:24) as a component of Red Hat Enterprise Linux 9 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs?arch=src&rpmmod=nodejs:24

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • nodejs (nodejs:26) as a component of Red Hat Enterprise Linux 9 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/nodejs?rpmmod=nodejs:26

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • npm (nodejs:26) as a component of Red Hat Enterprise Linux 9 · known not affected

    Vendor assessment for this product only.

    Reason: vulnerable code not present

    pkg:rpm/redhat/npm?rpmmod=nodejs:26

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • istio-proxy-selinux as a component of OpenShift Service Mesh 3 · under investigation

    Vendor assessment for this product only.

    pkg:rpm/redhat/istio-proxy-selinux

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00
  • istio-proxy.src as a component of OpenShift Service Mesh 3 · under investigation

    Vendor assessment for this product only.

    pkg:rpm/redhat/istio-proxy?arch=src

    Red Hat · CVE-2026-69186 · Updated 2026-10-22T20:32:22+00:00

All CVSS metrics

  • MEDIUM 5.3 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
  • MEDIUM 5.3 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

References

Exploit-tagged references (not proof of a PoC)

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS