Vulnerability · Published Jun 19, 2026 · Assigned by mitre
CVE-2026-56131
Medium 4.9
In plain English
A medium-severity use-after-free in libexpat from libexpat project. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)4.9Medium
Exploit odds (30 days)0.2%top 92.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219 situation).
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.21 | expat | 2.8.2-r0 | ALPINE-CVE-2026-56131 |
| Alpine:v3.22 | expat | 2.8.2-r0 | ALPINE-CVE-2026-56131 |
| Alpine:v3.23 | expat | 2.8.2-r0 | ALPINE-CVE-2026-56131 |
| Alpine:v3.24 | expat | 2.8.2-r0 | ALPINE-CVE-2026-56131 |
| Debian:12 | expat | 2.5.0-1+deb12u3 | DEBIAN-CVE-2026-56131 |
| Debian:13 | expat | 2.8.2-1~deb13u1 | DEBIAN-CVE-2026-56131 |
| Debian:14 | expat | 2.8.2-1 | DEBIAN-CVE-2026-56131 |
| Ubuntu:22.04:LTS | cadaver | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:24.04:LTS | cadaver | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:25.10 | cadaver | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.04:LTS | cadaver | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.10 | cadaver | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:22.04:LTS | expat | 2.4.7-1ubuntu0.9 | USN-8813-1 |
| Ubuntu:22.04:LTS | expat | 2.4.7-1ubuntu0.9 | UBUNTU-CVE-2026-56131 |
| Ubuntu:24.04:LTS | expat | 2.6.1-2ubuntu0.6 | UBUNTU-CVE-2026-56131 |
| Ubuntu:24.04:LTS | expat | 2.6.1-2ubuntu0.6 | USN-8813-1 |
| Ubuntu:25.10 | expat | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.04:LTS | expat | 2.7.4-1ubuntu0.2 | USN-8813-1 |
| Ubuntu:26.04:LTS | expat | 2.7.4-1ubuntu0.2 | UBUNTU-CVE-2026-56131 |
| Ubuntu:22.04:LTS | insighttoolkit4 | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:22.04:LTS | matanza | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:24.04:LTS | matanza | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:25.10 | matanza | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.04:LTS | matanza | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.10 | matanza | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:25.10 | swish-e | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.10 | swish-e | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:22.04:LTS | tdom | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:24.04:LTS | tdom | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:25.10 | tdom | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.04:LTS | tdom | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.10 | tdom | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:22.04:LTS | wbxml2 | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:24.04:LTS | wbxml2 | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:25.10 | wbxml2 | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.04:LTS | wbxml2 | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.10 | wbxml2 | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:25.10 | xmlrpc-c | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.04:LTS | xmlrpc-c | no fix listed | UBUNTU-CVE-2026-56131 |
| Ubuntu:26.10 | xmlrpc-c | no fix listed | UBUNTU-CVE-2026-56131 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| libexpat project | libexpat | 0 – before 2.8.2 |
Weakness: CWE-416 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L