synced 12 MIN AGO
01 Record

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.

MediumPUBLISHEDCNA: mitre
CNA base score4.9 CVSS v3.xCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

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.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
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

VendorProductVersionsPlatforms
libexpat projectlibexpat0 to < 2.8.4—

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+esm13
    Available 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+esm14
    Available 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+esm5
    Available 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+esm3
    Available 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.