CVE-2026-76957
libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.
02 Description
libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.
03 Exploitation and scoring
- Exploitation
- Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
- SSVC decision
- ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
- AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
- Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
- EPSS probability
- 0.10% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 1.0% of scored records. A rank, not a probability.
- NVD base score
- 7.8 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- NVD analysis status
- Analyzed. NVD last modified this record on 2026-09-08.
- Red Hat severity
- Moderate. Red Hat's rating for its own products, not a CVSS rating.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2026-08-20 04:28Z2 MO AGO
- Last updated
- 2026-08-20 15:26Z2 MO AGO
- Reserved
- 2026-08-20
- Assigning CNA
- mitre
- Record state
- PUBLISHED
- Severity
- Medium (CVSS 4.9)
- CNA CVSS vector
- CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
- Weaknesses
- Data version
- 5.2
- Document digest
- a62dc7bfe516a14dcc8e966b73824260b57750c9a6bbe234df7d456b6ce859ab
05 Affected products
06 References
07 Fixed in
Debian 12
- expat Fixed in 2.5.0-1+deb12u3
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- expat Fixed in 2.9.0-1~deb13u1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- expat Fixed in 2.8.4-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 16.04 LTS
- cadaver No fix yet
- gdcm No fix yet
- insighttoolkit4 No fix yet
- matanza No fix yet
- smart No fix yet
- tdom No fix yet
- wbxml2 No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 18.04 LTS
- cadaver No fix yet
- gdcm No fix yet
- insighttoolkit4 No fix yet
- matanza No fix yet
- smart No fix yet
- tdom No fix yet
- vnc4 No fix yet
- wbxml2 No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 20.04 LTS
- cadaver No fix yet
- insighttoolkit4 No fix yet
- matanza No fix yet
- tdom No fix yet
- wbxml2 No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 22.04 LTS
- cadaver No fix yet
- expat Fixed in 2.4.7-1ubuntu0.9
- insighttoolkit4 No fix yet
- matanza No fix yet
- tdom No fix yet
- wbxml2 No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 24.04 LTS
- cadaver No fix yet
- expat Fixed in 2.6.1-2ubuntu0.6
- matanza No fix yet
- tdom No fix yet
- wbxml2 No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 26.04 LTS
- cadaver No fix yet
- expat Fixed in 2.7.4-1ubuntu0.2
- matanza No fix yet
- tdom No fix yet
- wbxml2 No fix yet
- xmlrpc-c No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 26.10
- cadaver No fix yet
- matanza No fix yet
- swish-e No fix yet
- tdom No fix yet
- wbxml2 No fix yet
- xmlrpc-c No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 14.04 LTS
- coin3 No fix yet
- expat Fixed in 2.1.0-4ubuntu1.4+esm13Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro
- vnc4 No fix yet
- vtk No fix yet
- xmlrpc-c No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 16.04 LTS
- ayttm No fix yet
- cableswig No fix yet
- coin3 No fix yet
- expat Fixed in 2.1.0-7ubuntu0.16.04.5+esm14Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro
- libxmltok No fix yet
- swish-e No fix yet
- vnc4 No fix yet
- vtk No fix yet
- xmlrpc-c No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 18.04 LTS
- coin3 No fix yet
- expat Fixed in 2.2.5-3ubuntu0.9+esm5Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro
- libxmltok No fix yet
- swish-e No fix yet
- xmlrpc-c No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 20.04 LTS
- expat Fixed in 2.2.9-1ubuntu0.8+esm3Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro
- libxmltok No fix yet
- swish-e No fix yet
- xmlrpc-c No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 22.04 LTS
- libxmltok No fix yet
- swish-e No fix yet
- xmlrpc-c No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 24.04 LTS
- libxmltok No fix yet
- swish-e No fix yet
- xmlrpc-c No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 26.04 LTS
- swish-e No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.