Critical (9.8) in libexpat project libexpat. EPSS 1.1% chance of exploitation in the next 30 days.
An issue was discovered in libexpat before 2.6.3. dtdCopy in xmlparse.c can have an integer overflow for nDefaultAtts on 32-bit platforms (where UINT_MAX equals SIZE_MAX).
Severity
CVSS 3.1
9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
1.1% chance of exploitation in the next 30 days; higher than 66% of CVEs (scores of 2026-10-31)