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Fencer Intel
medium 6.9

CVE-2026-25210 json

In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize because there is no integer overflow c…

published 9mo ago modified 3mo ago also EUVD-2026-5042 , JLSEC-2026-380

cvss
6.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 11%
public exploits
0
none known

Summary

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.

Patch / fix

  • julia Expat_jll 2.7.5+0
  • libexpat project libexpat 2.7.4
  • Siemens RUGGEDCOM RST2428P V4.0
  • expat Debian 12 2.5.0-1+deb12u4
  • expat Debian 13 2.8.2-1~deb13u1
  • expat Debian 14 2.7.4-1

debian advisories DEBIAN-CVE-2026-25210

  • expat Ubuntu 22.04 LTS 2.4.7-1ubuntu0.7
  • expat Ubuntu 24.04 LTS 2.6.1-2ubuntu0.4
  • expat Ubuntu 25.10 2.7.1-2ubuntu0.2
  • expat Ubuntu Pro 14.04 LTS 2.1.0-4ubuntu1.4+esm11
  • expat Ubuntu Pro 16.04 LTS 2.1.0-7ubuntu0.16.04.5+esm11
  • expat Ubuntu Pro 18.04 LTS 2.2.5-3ubuntu0.9+esm3
  • expat Ubuntu Pro 20.04 LTS 2.2.9-1ubuntu0.8+esm1
  • libxmltok Ubuntu Pro 16.04 LTS 1.2-3ubuntu0.16.04.1~esm5

ubuntu advisories UBUNTU-CVE-2026-25210

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • expat Linux Micro 6.1 2.8.5-slfo.1.1_1.1
  • expat SLE Module for Basesystem 15 SP7 2.8.5-150700.3.15.1
  • expat Linux Micro 6.0 2.8.5-159998.1.1
  • expat SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +10 more 2.8.5-150400.3.40.1
  • expat SLE Micro 5.5, SLE Micro 5.4, SLE Micro 5.3 +1 more 2.7.1-150400.3.34.1
  • expat SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 2.7.1-160000.4.1
  • expat SLE Module for Basesystem 15 SP7 2.7.1-150700.3.9.2
  • expat Linux Micro 6.1 2.7.1-slfo.1.1_4.1

suse advisories SUSE-SU-2026:24554-1SUSE-SU-2026:4619-1SUSE-SU-2026:24323-1SUSE-SU-2026:4623-1SUSE-SU-2026:4615-1SUSE-SU-2026:0826-1

  • expat openSUSE Leap 16.0 2.7.1-160000.4.1
  • expat openSUSE Tumbleweed 2.7.4-1.1

opensuse advisories openSUSE-SU-2026:20306-1openSUSE-SU-2026:10144-1

  • expat Alpine 3.24, Alpine 3.23, Alpine 3.22 +2 more 2.7.4-r0
  • qt6-qtwebengine Alpine 3.24 6.11.1-r2

alpine advisories ALPINE-CVE-2026-25210

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • expat CBL-Mariner 2.0, Azure Linux 3.0 2.6.4-4

azure linux advisories AZL-75815AZL-76340

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Is CVE-2026-25210 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-25210 updated cvss 6.9

libexpat: libexpat: Information disclosure and data integrity issues due to integer overflow in buffer reallocation

  • Red Hat Enterprise Linux 6 expat, compat-expat1 Red Hat Enterprise Linux 7 expat Red Hat Enterprise Linux 8 expat, mingw-expat, mingw32-expat, mingw64-expat Red Hat Enterprise Linux 9 expat Red Hat Enterprise Linux 10 expat
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-26-155-04 updated cvss 7.8

Hitachi Energy RTU500

  • Hitachi Energy RTU500 series CMU Firmware vers:RTU500_series_CMU_Firmware/>=12.7.1, <=12.7.7, vers:RTU500_series_CMU_Firmware/>=13.5.1, <=13.5.4, vers:RTU500_series_CMU_Firmware/>=13.6.1, <=13.6.3, vers:RTU500_series_CMU_Firmware/>=13.7.1, <=13.7.8
    affected: vendor fix, mitigation

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
6mo ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 6.9 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
OSV 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
julia Expat_jll
<2.7.5+0
2.7.5+0

Affected products

  • libexpat project libexpat
  • Siemens RUGGEDCOM RST2428P

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.