CVE-2026-66337
MEDIUM 6.5 ALL-YEARSA flaw was found in libsoup. An unsigned integer underflow in the soup_filter_input_stream_read_until() function causes a heap buffer over-read when parsing multipart HTTP responses. A malicious HTTP server can exploit this by sending a crafted multipart response, potentially causing the client application to crash or disclose sensitive heap memory.
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
- ConfidentialityLow
- 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 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-125: Out-of-bounds Read
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
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:N/S:U/C:L/I:N/A:L - MEDIUM 6.5 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
References
Exploit-tagged references (not proof of a PoC)
- https://bugzilla.redhat.com/show_bug.cgi?id=2506949 CVE record · redhat · Updated 2026-07-24T23:01:20.983Z
NVD · CVE-2026-66337 · Updated 2026-08-24T16:44:56.007
Red Hat · CVE-2026-66337 · Updated 2026-07-25T00:06:05+00:00
Advisories
- https://access.redhat.com/security/cve/CVE-2026-66337 CVE record · redhat · Updated 2026-07-24T23:01:20.983Z
NVD · CVE-2026-66337 · Updated 2026-08-24T16:44:56.007
Red Hat · CVE-2026-66337 · Updated 2026-07-25T00:06:05+00:00 - https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-66337.json Red Hat · CVE-2026-66337 · Updated 2026-07-25T00:06:05+00:00
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-48753 EUVD · EUVD-2026-48753
Technical & other
- https://www.cve.org/CVERecord?id=CVE-2026-66337 Red Hat · CVE-2026-66337 · Updated 2026-07-25T00:06:05+00:00
- https://nvd.nist.gov/vuln/detail/CVE-2026-66337 Red Hat · CVE-2026-66337 · Updated 2026-07-25T00:06:05+00:00
Sources: NVD · CVE.org · All sources and attribution · EPSS