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Fencer Intel
medium 5.5

CVE-2023-52426 json

libexpat through 2.5.0 allows recursive XML Entity Expansion if `XML_DTD` is undefined at compile...

published 2y ago modified last mo. also EUVD-2023-57053 , JLSEC-2025-59

cvss
5.5
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 34%
public exploits
0
none known

Summary

libexpat through 2.5.0 allows recursive XML Entity Expansion if XML_DTD is undefined at compile time.

Patch / fix

  • julia Expat_jll 2.6.2+0
  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP V3.1.5
  • Siemens SINEC NMS V3.0
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP V3.1.5
  • expat Debian 14, Debian 13 2.6.0-1

debian advisories DEBIAN-CVE-2023-52426

  • expat Ubuntu 24.04 LTS 2.6.0-1

ubuntu advisories UBUNTU-CVE-2023-52426

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 2.7.1-slfo.1.1_1.1
  • expat Linux Micro 6.0 2.7.1-1.1

suse advisories SUSE-SU-2025:20311-1SUSE-SU-2025:20207-1

  • expat openSUSE Tumbleweed 2.6.0-1.1

opensuse advisories openSUSE-SU-2024:13695-1

  • expat Alpine 3.24, Alpine 3.23, Alpine 3.22 +6 more 2.6.0-r0

alpine advisories ALPINE-CVE-2023-52426

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 2.6.2-2
  • expat Azure Linux 3.0 2.6.2-1

azure linux advisories AZL-34208AZL-34684

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-2023-52426 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-2023-52426 updated cvss 5.5

expat: recursive XML entity expansion vulnerability

  • Red Hat Enterprise Linux 6 expat Red Hat Enterprise Linux 7 expat, firefox, thunderbird
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 firefox, xmlrpc-c, thunderbird, xmlrpc-c-c++, xmlrpc-c-client, xmlrpc-c-client++
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise Linux 8 expat, firefox, thunderbird Red Hat Enterprise Linux 9 expat, firefox, firefox-x11, thunderbird Red Hat JBoss Core Services 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-23-348-10 updated cvss 5.5

Siemens SIMATIC S7-1500

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.0, < 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.0, < 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.0, < 3.1.5
    affected: fixed in V3.1.5, mitigation support.industry.siemens.com

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
partial
Assessed
2y ago

Exploit prediction

0.39% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-14).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
julia Expat_jll
<2.6.2+0
2.6.2+0

Affected products

  • Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
  • Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
  • Siemens SINEC NMS
  • Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness
  • CWE-776 Improper Restriction of Recursive Entity References in DTDs

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.