libexpat through 2.9.0 contains a signed integer overflow vulnerability in storeAtts() in lib/xmlparse.c that allows attackers to trigger out-of-bounds writes via oversized attribute counts. Attackers can supply a multi-gigabyte document with a start tag carrying over 2^30 attributes to overflow attIndex and nPrefixes, crashing applications or corrupting heap memory.
| Version | Score | Severity | Vector String |
|---|---|---|---|
| 4.0 | 8.2 | High | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| 3.1 | 5.9 | Medium | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H |