Vulnerability details
CVE-2026-76641
libexpat libexpat
Expat Out-of-Bounds Read via dtdCopy
CVSS 4.0
8.7High
Official description
Expat through 2.8.3 contains an out-of-bounds read vulnerability that allows attackers to trigger memory corruption by processing XML with external entity parsers created via XML_ExternalEntityParserCreate. A struct size mismatch between ELEMENT_TYPE members causes storeAtts to read the attIndex member past allocated memory boundaries, resulting in failure to normalize whitespace in non-CDATA attributes or a wild pointer dereference causing a segfault. This vulnerability was introduced by the fix for CVE-2026-66046.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 8.7High | 4.0 | CVEProject cvelistV5 (CNA) (VulnCheck) | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| 7.5High | 3.1 | CVEProject cvelistV5 (CNA) (VulnCheck) | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| libexpat | libexpat | v ≤ 2.8.3 | CVEProject cvelistV5 (CNA) |
References and advisories
3
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Details
- Published
- 2026-08-20
- Last updated
- 2026-11-08
- State
- Published
- Assigner (CNA)
- VulnCheck
Exploit prediction (EPSS)
0.35%
Probability of exploitation in 30 days
29.1%
Percentile (among all CVEs)
SSVC assessment (CISA)
- Automatable
- Yes
- Exploitation
- None
- Technical impact
- Partial
Weaknesses (CWE)
- CWE-125Out-of-bounds Read