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Fencer Vulns
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 2026-01-30 9 mo ago modified 2026-07-18 3 mo 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

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
6 mo ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).

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 Vulns 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.