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Fencer Vulns
high 7.5

CVE-2026-45186 json

In libexpat before 2.8.1, the computational complexity of attribute name collision checks allows a denial of service via moderately sized c…

published 2026-05-10 6 mo ago modified 2026-10-15 25 d ago also EUVD-2026-28985 , JLSEC-2026-1223

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

In libexpat before 2.8.1, the computational complexity of attribute name collision checks allows a denial of service via moderately sized crafted XML input.

Patch / fix

  • julia Expat_jll 2.8.1+0
  • libexpat project libexpat 2.8.1
  • Red Hat Red Hat Enterprise Linux 10 0:2.7.3-1.el10_2.1
  • Red Hat Red Hat Enterprise Linux 8 0:2.5.0-2.el8_10
  • Red Hat Red Hat Enterprise Linux 9 0:2.5.0-6.el9_8.1
  • Red Hat Red Hat Discovery 2 1782159791, 1782166952
  • Red Hat Red Hat Update Infrastructure 5 1781525671, 1781525684, 1781525693, 1781525739, 1787135742, 1787241211, 1787241260
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.6
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.6
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.6
  • expat Debian 12 2.5.0-1+deb12u4
  • expat Debian 13 2.8.2-1~deb13u1
  • expat Debian 14 2.8.0-2

debian advisories DEBIAN-CVE-2026-45186

  • expat Ubuntu 24.04 LTS 2.6.1-2ubuntu0.5
  • expat Ubuntu 26.04 LTS 2.7.4-1ubuntu0.1

ubuntu advisories UBUNTU-CVE-2026-45186

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 hummingbird 1 2.8.5-1.1.hum1
  • expat RHEL 9 2.5.0-6.el9_8.1
  • expat RHEL 8 2.5.0-2.el8_10
  • expat RHEL 10.2 2.7.3-1.el10_2.1

red hat advisories RHSA-2026:77236RHSA-2026:23230RHSA-2026:22721RHSA-2026:22715

  • expat Linux Micro 6.1 2.8.5-slfo.1.1_1.1
  • MozillaFirefox SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 153.5.0-150400.157.16.1
  • MozillaFirefox SLES for SAP applications 16.0, SLES 16.0 153.5.0-160000.1.1
  • MozillaThunderbird SLE Workstation Extension 15 SP7, SLE Module for Package Hub 15 SP7 153.5.0-150400.13.9.1
  • 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 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 2.8.4-160000.1.1

suse advisories SUSE-SU-2026:24554-1SUSE-SU-2026:4834-1SUSE-SU-2026:4806-1SUSE-SU-2026:24260-1SUSE-SU-2026:4736-1SUSE-SU-2026:4619-1

  • MozillaFirefox openSUSE Leap 16.0 153.5.0-160000.1.1
  • expat openSUSE Leap 16.0 2.8.4-160000.1.1
  • python311 openSUSE Tumbleweed 3.11.16-1.1
  • python310 openSUSE Tumbleweed 3.10.21-1.1
  • expat openSUSE Tumbleweed 2.8.1-1.1

opensuse advisories openSUSE-SU-2026:22139-1openSUSE-SU-2026:21945-1openSUSE-SU-2026:11756-1openSUSE-SU-2026:11747-1openSUSE-SU-2026:10787-1

  • thunderbird AlmaLinux 9 153.5.0-1.el9_8.alma.1
  • thunderbird AlmaLinux 10 153.5.0-1.el10_2.alma.1
  • firefox AlmaLinux 8 153.5.0-1.el8_10
  • firefox AlmaLinux 9 153.5.0-1.el9_8
  • firefox-x11 AlmaLinux 9 153.5.0-1.el9_8
  • firefox AlmaLinux 10 153.5.0-1.el10_2
  • expat AlmaLinux 9 2.5.0-6.el9_8.1
  • expat AlmaLinux 10 2.7.3-1.el10_2.1

almalinux advisories ALSA-2026:93443ALSA-2026:90895ALSA-2026:89756ALSA-2026:89757ALSA-2026:89758ALSA-2026:23230

  • thunderbird Rocky Linux 9 153.5.0-1.el9_8
  • firefox Rocky Linux 10 153.5.0-1.el10_2
  • firefox Rocky Linux 9 153.5.0-1.el9_8
  • firefox Rocky Linux 8 153.5.0-1.el8_10
  • thunderbird Rocky Linux 10 153.5.0-1.el10_2
  • expat Rocky Linux 10 2.7.3-1.el10_2.1
  • expat Rocky Linux 9 2.5.0-6.el9_8.1
  • expat Rocky Linux 8 2.5.0-2.el8_10

rocky linux advisories RLSA-2026:93443RLSA-2026:89758RLSA-2026:89757RLSA-2026:89756RLSA-2026:90895RLSA-2026:22715

  • expat Alpine 3.24, Alpine 3.23, Alpine 3.22 +2 more 2.8.1-r0

alpine advisories ALPINE-CVE-2026-45186

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 Azure Linux 3.0 2.8.2-1

azure linux advisories AZL-86340

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-2026-45186 updated cvss 7.5

libexpat: denial of service via crafted XML input

  • Red Hat Enterprise Linux 6 expat, compat-expat1
    affected: workaround, no fix available, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 7 expat, firefox Red Hat Enterprise Linux 8 xmlrpc-c, mingw-expat, thunderbird, xmlrpc-c-c++, mingw32-expat, mingw64-expat, +2 more
    affected: workaround, no fix available
  • Red Hat Discovery 2 discovery/discovery-ui-rhel9 1782166952, discovery/discovery-server-rhel9 1782159791
    fixed: vendor fix RHSA-2026:29197
  • Red Hat Enterprise Linux AppStream (v. 8) firefox 153.5.0-1.el8_10
    fixed: vendor fix RHSA-2026:89756
  • Red Hat Enterprise Linux AppStream (v. 9) firefox 153.5.0-1.el9_8, firefox-x11 153.5.0-1.el9_8, thunderbird 153.5.0-1.el9_8
    fixed: vendor fix RHSA-2026:23230
  • Red Hat Enterprise Linux AppStream (v. 10) firefox 153.5.0-1.el10_2, thunderbird 153.5.0-1.el10_2
    fixed: vendor fix RHSA-2026:22715
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) thunderbird 153.5.0-1.el9_4
    fixed: vendor fix RHSA-2026:95597
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) thunderbird 153.5.0-1.el9_6
    fixed: vendor fix RHSA-2026:95596
show 7 more
  • Red Hat Enterprise Linux BaseOS (v. 8) expat 2.5.0-2.el8_10
    fixed: vendor fix RHSA-2026:22721
  • Red Hat Enterprise Linux BaseOS (v. 9) expat 2.5.0-6.el9_8.1
    fixed: vendor fix RHSA-2026:23230
  • Red Hat Enterprise Linux BaseOS (v. 10) expat 2.7.3-1.el10_2.1
    fixed: vendor fix RHSA-2026:22715
  • Red Hat Hardened Images expat 2.8.5-1.1.hum1
    fixed: vendor fix RHSA-2026:77236
  • Red Hat JBoss Core Services 2.4.62.SP4
    fixed: vendor fix RHSA-2026:27201
  • Red Hat Update Infrastructure 5 rhui5/cds-rhel9 1781525684, rhui5/rhua-rhel9 1781525739, rhui5/haproxy-rhel9 1781525671, rhui5/rhua-tp-rhel9 1787241260, rhui5/installer-rhel9 1781525693, rhui5/installer-tp-rhel9 1787135742, +1 more
    fixed: vendor fix RHSA-2026:58981
  • Red Hat Update Infrastructure 5 rhui5/cds-tp-rhel9 1787241206, rhui5/cds-kubernetes-rhel9 1781525677
    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
5 mo ago

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/libexpat/libexpat/pull/1216 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 2.9 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
julia Expat_jll
<2.8.1+0
2.8.1+0

Affected products

  • libexpat project libexpat
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat JBoss Core Services 2.4.62.SP4
  • Red Hat Red Hat Discovery 2
  • Red Hat Red Hat Update Infrastructure 5
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity

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.