Use after free in libexpat
Priority LOW 33CWE-416Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 1 fixed, 8 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.
Summary
libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00107 1st percentileScored 2026-11-07
Fix Partial libexpat (libexpat project): 2.8.4Red Hat: 2 advisoriesRed Hat: 1 fixed, 8 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| libexpat project | libexpat | before 2.8.4 | 2.8.4 | Patch available | CNA |
- libexpat Vendorlibexpat project Affected before 2.8.4 Fixed in 2.8.4 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:* | before 2.8.4 | Vulnerable | libexpat project |
- cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:* Versions before 2.8.4 Vulnerable ·libexpat project
Remediation
- Fix · CNA libexpat (libexpat project) Fixed in 2.8.4
Red Hat 2 advisories
- RHSA-2026:65568 Released 2026-09-08 · Red Hat rating ImportantRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images expat-2.8.4-0.1.hum1@aarch64, expat-2.8.4-0.1.hum1@src, expat-2.8.4-0.1.hum1@x86_64 +4
- RHSA-2026:60451 Released 2026-08-27 · Red Hat rating ModerateRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images expat-2.8.3-0.1.1.hum1@aarch64, expat-2.8.3-0.1.1.hum1@src, expat-2.8.3-0.1.1.hum1@x86_64 +4
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
libexpat 2.8.4
2 records Highest priority Priority LOW 2 LOW
Other records, highest priority first
- TI-2026-53752 In libexpat 2.8.2 and 2.8.3 before 2.8.4, misinterpretation of getentropy's return code…Priority LOW 39
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | — |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
| Red Hat Hardened Images | Fixed | RHSA-2026:60451, RHSA-2026:65568 |
Not affected: 1 product
- Red Hat OpenShift AI (RHOAI)
Timeline
- 2026-10-02 Threatist record created from CVE-2026-76957
- 2026-10-03 Alias added: GHSA-vfgp-2986-rm7g
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 Affected versions changed · Red Hat
References
More libexpat project Libexpat vulnerabilities
- TI-2022-09008 In Expat (aka libexpat) before 2.4.5, there is an integer overflow in storeRawNames. CVSS 3.1CRITICAL 9.8
- TI-2026-79488 Billion laughs detection delay in libexpat enables denial of service CVSS 4.0HIGH 8.7
- TI-2022-08947 xmlparse.c in Expat (aka libexpat) before 2.4.5 allows attackers to insert… CVSS 3.1CRITICAL 9.8
- TI-2021-20962 In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in the… CVSS 3.1HIGH 8.8
- TI-2021-21076 In doProlog in xmlparse.c in Expat (aka libexpat) before 2.4.3, an integer overflow exists for m_groupSize. CVSS 3.1HIGH 8.1
- TI-2016-00645 Expat allows context-dependent attackers to cause a denial of service (crash) or possibly… CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-76957 · CVE Program
- CVE-2026-76957 · NVD
- FIRST EPSS
- GHSA-vfgp-2986-rm7g · GitHub Advisory Database · CC BY 4.0
- CVE-2026-76957 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences