5.9

CVE-2026-56412: libexpat_project libexpat Use After Free

CVSS: 5.9v3.1MediumAnalyzed
AliasesALPINE-CVE-2026-56412UBUNTU-CVE-2026-56412DEBIAN-CVE-2026-56412
Published 21-06-2026Last modified 22-06-2026
Open JSON

Vulnerability summary

CVE-2026-56412 is a medium (CVSS 5.9) Use After Free vulnerability in libexpat_project libexpat. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7% of scored vulnerabilities.

Overall risk
24/100
0100
Low · default modelHow is this calculated?
CVSS score
5.9/10
010
Medium · v3.1 (NVD)
EPSS score
0.18%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 10 · Related 10
MGASA-2026-0352OPENSUSE-SU-2026:11584-1OPENSUSE-SU-2026:21945-1SUSE-SU-2026:23894-1SUSE-SU-2026:23912-1SUSE-SU-2026:4615-1

Timeline

  1. 21-06-2026
    PublishedVulnerability first disclosed.
  2. 22-06-2026
    Last modifiedVulnerability information updated.

Description

libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219.

CVSS metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.18%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

0.00 pp

From 0.18% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.18%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu16 products
  • ayttmAll versions (No fix recorded)
  • cableswigAll versions (No fix recorded)
  • cadaverAll versions (No fix recorded)
  • coin3All versions (No fix recorded)
  • expat< 2.1.0-4ubuntu1.4+esm12 | < 2.1.0-7ubuntu0.16.04.5+esm13 | < 2.2.5-3ubuntu0.9+esm4 | < 2.2.9-1ubuntu0.8+esm2 | < 2.4.7-1ubuntu0.8 | < 2.6.1-2ubuntu0.5 | All versions (No fix recorded) | < 2.7.4-1ubuntu0.1
Chainguard4 products
  • expat< 2.8.2-r0
  • expat-dev< 2.8.2-r0
  • expat-doc< 2.8.2-r0
  • libexpat1< 2.8.2-r0
Wolfi4 products
  • expat< 2.8.2-r0
  • expat-dev< 2.8.2-r0
  • expat-doc< 2.8.2-r0
  • libexpat1< 2.8.2-r0
Alpine1 product
  • expat< 2.8.2-r0
Debian1 product
  • expat< 2.5.0-1+deb12u3 | < 2.8.2-1~deb13u1 | < 2.8.2-1
Libexpat_project1 product

6 vendors · 27 products

References

8 links