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Vulnerability record · CVE-2026-25210 · published 30 January 2026

CVE-2026-25210: Libexpat project libexpat integer overflow vulnerability

LLibexpat Project · Libexpat

In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize because there is no integer overflow check for tag buffer reallocation.

7.8 CVSS 3.1 High EPSS 0.20% · top 91.1% CWE-190 · Integer overflow
7.8CVSS 3.1 base score
0.20%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References
17 Jun 2026Last modified by NVD

Description

In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize because there is no integer overflow check for tag buffer reallocation.

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/1075 Issue TrackingPatch
https://github.com/libexpat/libexpat/pull/1075/commits/9c2d990389e6abe2e44527eeaa8b39f16fe859c7 Patch
https://cert-portal.siemens.com/productcert/html/ssa-253495.html

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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-2026-25210), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.