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Vulnerability record · CVE-2026-76957 · published 20 August 2026

CVE-2026-76957: Libexpat project libexpat use after free vulnerability

LLibexpat Project · Libexpat

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.

7.8 CVSS 3.1 High EPSS 0.11% · top 99.0% CWE-416 · Use after free
7.8CVSS 3.1 base score
0.11%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
8 Sep 2026Last modified by NVD

Description

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/libexpat/libexpat/pull/1322 Issue TrackingPatchVendor Advisory
https://github.com/libexpat/libexpat/pull/1329 Issue TrackingPatch

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2024-45491Libexpat project libexpat integer overflow vulnerabilityAn issue was discovered in libexpat before 2.6.3. dtdCopy in xmlparse.c can have an integer overflow for nDefaultAtts on 32-bit platforms (where UINT…EPSS 1.1%9.8CVE-2024-45492Libexpat project libexpat integer overflow vulnerabilityAn issue was discovered in libexpat before 2.6.3. nextScaffoldPart in xmlparse.c can have an integer overflow for m_groupSize on 32-bit platforms (wh…EPSS 1.4%9.8CVE-2022-25315Libexpat project libexpat integer overflow vulnerabilityIn Expat (aka libexpat) before 2.4.5, there is an integer overflow in storeRawNames.EPSS 4.8%9.8CVE-2022-25235Libexpat project libexpat vulnerabilityxmltok_impl.c in Expat (aka libexpat) before 2.4.5 lacks certain validation of encoding, such as checks for whether a UTF-8 character is valid in a c…EPSS 5.0%9.8CVE-2022-25236Libexpat project libexpat exposure of resource to wrong sphere vulnerabilityxmlparse.c in Expat (aka libexpat) before 2.4.5 allows attackers to insert namespace-separator characters into namespace URIs.EPSS 36%9.8CVE-2022-23852Libexpat project libexpat integer overflow vulnerabilityExpat (aka libexpat) before 2.4.4 has a signed integer overflow in XML_GetBuffer, for configurations with a nonzero XML_CONTEXT_BYTES.EPSS 4.6%9.8CVE-2022-22822Libexpat project libexpat integer overflow vulnerabilityaddBinding in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.EPSS 4.8%9.8CVE-2022-22823Libexpat project libexpat integer overflow vulnerabilitybuild_model in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.EPSS 3.4%

Source: NIST National Vulnerability Database (record CVE-2026-76957), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.