CVE-2026-25210: libexpat_project libexpat Integer Overflow or Wraparound

Vulnerability summary

CVE-2026-25210 is a high (CVSS 7.8) Integer Overflow or Wraparound vulnerability in libexpat_project libexpat. EPSS estimates a 0.21% chance of exploitation in the next 30 days, higher than 11% of scored vulnerabilities.

Timeline

1. 30-01-2026
   PublishedVulnerability first disclosed.
2. 02-06-2026
   Last modifiedVulnerability information updated.

Description

In libexpat before 2.7.4, the doContent function does not properly determine the buffer size bufSize because there is no integer overflow check for tag buffer reallocation.

• CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.