November 14, 2026

CVE Watchtower

CVE-2026-124317libexpat libexpat

NVD

Vulnerability Summary

libexpat through 2.10.0 contains an out-of-bounds read vulnerability in unknown_toUtf8() and unknown_toUtf16() in xmltok.c when handling application-registered unknown encodings. Attackers can supply a document ending in a truncated multibyte sequence so the convert callback reads past the parse buffer, leaking adjacent memory or crashing applications.
Severity Level
MEDIUM(6.3)
Published Date
Nov 7, 2026
Last Modified
Nov 11, 2026
Exploitation Status
No confirmed exploitation yet
EPSS Score (30-Day)
0.25%Probability
Root Weakness (CWE)
CWE-126 ↗
See the MITRE CWE entry for the full definition of this weakness.
CVSS v4.0 Base Metrics — Score 6.3 (MEDIUM)
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
Attack VectorNetwork
Attack ComplexityHigh
Attack RequirementsPresent
Privileges RequiredNone
User InteractionNone
Confidentiality (Vulnerable System)Low
Integrity (Vulnerable System)None
Availability (Vulnerable System)Low
Confidentiality (Subsequent System)None
Integrity (Subsequent System)None
Availability (Subsequent System)None
Show CVSS v3.x metrics (score 4.8)
CVSS v3.1 Base Metrics — Score 4.8 (MEDIUM)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityLow
IntegrityNone
AvailabilityLow

Affected & Patched Versions

Affected Versions
  • libexpat libexpat <= 2.10.0
Patched Versions
  • libexpat libexpat 2.10.0

What to do

Fix it during your normal patch cycle. No exploitation is confirmed yet.

  1. Check whether you run libexpat libexpat and which version.
  2. Update to a patched version listed above, then confirm the new version.

Timeline

  • Nov 7, 2026Published
  • Nov 11, 2026Record last modified

Score, severity and exploitation changes are tracked from the day Watchtower started logging them.

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External References

Data last checked: Nov 14, 2026 03:22 UTC