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Fencer Vulns
medium 5.9

CVE-2026-102633 json

libexpat 2.7.2 through 2.8.5 Integer Overflow in expat_realloc

published 2026-09-29 41 d ago modified 2026-09-29 40 d ago also EUVD-2026-89028

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc() function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial of service.

Patch / fix

  • expat Debian 12 2.5.0-1+deb12u5
  • expat Debian 13 2.9.0-1~deb13u1
  • expat Debian 14 2.8.5-2

debian advisories DEBIAN-CVE-2026-102633

  • expat SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 2.8.5-160000.1.1
  • 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 SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.8.5-21.55.1

suse advisories SUSE-SU-2026:24460-1SUSE-SU-2026:24469-1SUSE-SU-2026:24554-1SUSE-SU-2026:4619-1SUSE-SU-2026:24323-1SUSE-SU-2026:4623-1

  • expat openSUSE Leap 16.0 2.8.5-160000.1.1
  • expat openSUSE Tumbleweed 2.8.5-1.1

opensuse advisories openSUSE-SU-2026:22177-1openSUSE-SU-2026:11981-1

  • expat AlmaLinux 8 2.5.0-6.el8_10
  • expat AlmaLinux 9 2.5.0-6.el9_8.7
  • expat AlmaLinux 10 2.7.3-1.el10_2.7

almalinux advisories ALSA-2026:92323ALSA-2026:88247ALSA-2026:88248

  • expat Rocky Linux 8 2.5.0-6.el8_10
  • expat Rocky Linux 10 2.7.3-1.el10_2.7
  • expat Rocky Linux 9 2.5.0-6.el9_8.7

rocky linux advisories RLSA-2026:92323RLSA-2026:88248RLSA-2026:88247

  • expat Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 2.9.0-r0

alpine advisories ALPINE-CVE-2026-102633

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

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-2026-102633 updated cvss 5.9

expat: expat: Denial of Service via integer overflow in expat_realloc

  • Red Hat Enterprise Linux 6 expat, compat-expat1
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 expat, firefox, firefox 140.17.0-1.el10_2 Red Hat Enterprise Linux 8 firefox, xmlrpc-c, mingw-expat, thunderbird, xmlrpc-c-c++, mingw32-expat, +5 more Red Hat Enterprise Linux 9 firefox, firefox-x11, thunderbird, firefox 140.17.0-1.el10_2, thunderbird 140.17.0-1.el10_2 Red Hat Enterprise Linux 10 firefox 140.17.0-1.el10_2, thunderbird 140.17.0-1.el10_2 Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-dashboard-rhel9
    under investigation
  • Red Hat Cost Management On-Premise 1 costmanagement/costmanagement-ui-rhel10 1793825318
    fixed: vendor fix RHSA-2026:95365
  • Red Hat Discovery 2 discovery/discovery-ui-rhel9 1793733716, discovery/discovery-server-rhel9 1793734080
    fixed: vendor fix RHSA-2026:94802
  • Red Hat Enterprise Linux AppStream (v. 9) expat-devel 2.5.0-6.el9_8.7, expat-debuginfo 2.5.0-6.el9_8.7, expat-debugsource 2.5.0-6.el9_8.7
    fixed: vendor fix RHSA-2026:88247
  • Red Hat Enterprise Linux AppStream (v. 10) expat-devel 2.7.3-1.el10_2.7, expat-debuginfo 2.7.3-1.el10_2.7, expat-debugsource 2.7.3-1.el10_2.7
    fixed: vendor fix RHSA-2026:88248
  • Red Hat Enterprise Linux BaseOS (v. 8) expat 2.5.0-6.el8_10
    fixed: vendor fix RHSA-2026:92323
show 4 more
  • Red Hat Enterprise Linux BaseOS (v. 9) expat 2.5.0-6.el9_8.7
    fixed: vendor fix RHSA-2026:88247
  • Red Hat Enterprise Linux BaseOS (v. 10) expat 2.7.3-1.el10_2.7
    fixed: vendor fix RHSA-2026:88248
  • Red Hat Update Infrastructure 5 rhui5/cds-rhel9 1793005764, rhui5/rhua-rhel9 1793005812, rhui5/haproxy-rhel9 1793004999, rhui5/installer-rhel9 1793004989, rhui5/cds-kubernetes-rhel9 1793005771
    fixed: vendor fix RHSA-2026:89907
  • Red Hat Hardened Images expat Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9
    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 SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
41 d ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 8.2 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 4.0 8.2 CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • libexpat libexpat

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.