In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c…
Priority LOW 31CWE-821Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · Low
- Fix status
- Partial Red Hat: 7 fixed, 7 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold backing array reallocation is mishandled when there is data-structure sharing across parsers.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00135 2nd percentileScored 2026-11-07
Fix Partial libexpat (libexpat project): 2.8.2Red Hat: 5 advisoriesRed Hat: 7 fixed, 7 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
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 2.8.2 | 2.8.2 | Patch available | CNA |
- libexpat Vendorlibexpat project Affected before 2.8.2 Fixed in 2.8.2 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:* | before 2.8.2 | Vulnerable | libexpat project |
- cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:* Versions before 2.8.2 Vulnerable ·libexpat project
Remediation
- Fix · CNA libexpat (libexpat project) Fixed in 2.8.2
Red Hat 5 advisories
- RHSA-2026:67956 Released 2026-09-16 · Red Hat rating ImportantRed Hat Update Infrastructure 5.3 security update
- Red Hat Update Infrastructure 5 registry.redhat.io/rhui5/cds-kubernetes-rhel9, registry.redhat.io/rhui5/cds-rhel9, registry.redhat.io/rhui5/haproxy-rhel9 +2
- RHSA-2026:64812 Released 2026-09-08 · Red Hat rating Moderateexpat security update
- Red Hat Enterprise Linux AppStream (v. 9) expat-devel-2.5.0-6.el9_8.3
- Red Hat Enterprise Linux BaseOS (v. 9) expat-2.5.0-6.el9_8.3
- RHSA-2026:64810 Released 2026-09-08 · Red Hat rating Moderateexpat security update
- Red Hat Enterprise Linux AppStream (v. 10) expat-devel-2.7.3-1.el10_2.3
- Red Hat Enterprise Linux BaseOS (v. 10) expat-2.7.3-1.el10_2.3
Show 2 more Red Hat advisories
- RHSA-2026:64809 Released 2026-09-08 · Red Hat rating Moderateexpat security update
- Red Hat Enterprise Linux BaseOS (v. 8) expat-2.5.0-2.el8_10.2, expat-devel-2.5.0-2.el8_10.2
- RHSA-2026:30647 Released 2026-06-28 · Red Hat rating ModerateRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images expat-2.8.2-1.hum1@aarch64, expat-2.8.2-1.hum1@src, expat-2.8.2-1.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 2.8.2
2 records Highest priority Priority LOW 2 LOW
Other records, highest priority first
- TI-2026-40509 Use after free in libexpatPriority LOW 22
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 planned: Out of support scope |
| 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 Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AppStream (v. 10) | Fixed | RHSA-2026:64810 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2026:64812 |
| Red Hat Enterprise Linux BaseOS (v. 10) | Fixed | RHSA-2026:64810 |
| Red Hat Enterprise Linux BaseOS (v. 8) | Fixed | RHSA-2026:64809 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2026:64812 |
| Red Hat Hardened Images | Fixed | RHSA-2026:30647 |
| Red Hat Update Infrastructure 5 | Fixed | RHSA-2026:67956 |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-56132
- 2026-10-03 Alias added: GHSA-425r-vwq2-26qv
- 2026-11-01 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-2026-56132 · CVE Program
- CVE-2026-56132 · NVD
- FIRST EPSS
- GHSA-425r-vwq2-26qv · GitHub Advisory Database · CC BY 4.0
- CVE-2026-56132 · 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