CVE-2026-66339
MEDIUM 6.5 ALL-YEARSA flaw was found in libsoup. After a CONNECT tunnel is established through an HTTP proxy, libsoup incorrectly attaches the Proxy-Authorization header to subsequent HTTPS requests sent through that tunnel to the destination server. This allows the destination server to capture proxy credentials, leading to information disclosure.
No known exploitation, public exploit, or elevated probability at this time. Track for changes.
Exploitation likelihood
0.2%chance of exploitation in 30 days · 16th percentile
Impact if exploited
6.5CVSS 3.1 · MEDIUM · CNA
- ConfidentialityHigh
- IntegrityNone
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ⚠User interaction: A user must take an action (click / open a file)
- ✓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 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.
Affected
Products Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9 Libsoup Enterprise Linux
Weakness (CWE)
- CWE-201: Insertion of Sensitive Information Into Sent Data
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
References and research data (JSON)
Vendor product assessments
libsoup3 as a component of Red Hat Enterprise Linux 10 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup3
- none available: Fix deferred
libsoup3-devel as a component of Red Hat Enterprise Linux 10 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup3-devel
- none available: Fix deferred
libsoup3-doc as a component of Red Hat Enterprise Linux 10 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup3-doc
- none available: Fix deferred
libsoup3.src as a component of Red Hat Enterprise Linux 10 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup3?arch=src
- none available: Fix deferred
libsoup as a component of Red Hat Enterprise Linux 6 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup
- none available: Fix deferred
libsoup-devel as a component of Red Hat Enterprise Linux 6 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup-devel
- none available: Fix deferred
libsoup.src as a component of Red Hat Enterprise Linux 6 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup?arch=src
- none available: Fix deferred
libsoup as a component of Red Hat Enterprise Linux 7 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup
- none available: Fix deferred
libsoup-devel as a component of Red Hat Enterprise Linux 7 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup-devel
- none available: Fix deferred
libsoup.src as a component of Red Hat Enterprise Linux 7 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup?arch=src
- none available: Fix deferred
libsoup as a component of Red Hat Enterprise Linux 8 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup
- none available: Fix deferred
libsoup-devel as a component of Red Hat Enterprise Linux 8 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup-devel
- none available: Fix deferred
libsoup.src as a component of Red Hat Enterprise Linux 8 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup?arch=src
- none available: Fix deferred
libsoup as a component of Red Hat Enterprise Linux 9 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup
- none available: Fix deferred
libsoup-devel as a component of Red Hat Enterprise Linux 9 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup-devel
- none available: Fix deferred
libsoup.src as a component of Red Hat Enterprise Linux 9 · known affected
Vendor assessment for this product only.
pkg:rpm/redhat/libsoup?arch=src
- none available: Fix deferred
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Gnome | Libsoup | * |
| Redhat | Enterprise Linux | 6.0 |
| Redhat | Enterprise Linux | 7.0 |
| Redhat | Enterprise Linux | 8.0 |
| Redhat | Enterprise Linux | 9.0 |
| Redhat | Enterprise Linux | 10.0 |
All CVSS metrics
- MEDIUM 6.5 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N - MEDIUM 6.5 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
References
Exploit-tagged references (not proof of a PoC)
- https://bugzilla.redhat.com/show_bug.cgi?id=2506951 CVE record · redhat · Updated 2026-07-24T23:01:15.634Z
NVD · CVE-2026-66339 · Updated 2026-08-24T16:44:01.940
Red Hat · CVE-2026-66339 · Updated 2026-07-25T00:06:04+00:00
Advisories
- https://access.redhat.com/security/cve/CVE-2026-66339 CVE record · redhat · Updated 2026-07-24T23:01:15.634Z
NVD · CVE-2026-66339 · Updated 2026-08-24T16:44:01.940
Red Hat · CVE-2026-66339 · Updated 2026-07-25T00:06:04+00:00 - https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-66339.json Red Hat · CVE-2026-66339 · Updated 2026-07-25T00:06:04+00:00
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-48751 EUVD · EUVD-2026-48751
Technical & other
- https://www.cve.org/CVERecord?id=CVE-2026-66339 Red Hat · CVE-2026-66339 · Updated 2026-07-25T00:06:04+00:00
- https://nvd.nist.gov/vuln/detail/CVE-2026-66339 Red Hat · CVE-2026-66339 · Updated 2026-07-25T00:06:04+00:00
Sources: NVD · CVE.org · All sources and attribution · EPSS