Summary
Expat is a C library for parsing XML documents.
Security Fix(es):
* expat: Expat: Denial of Service via quadratic complexity in attribute processing (CVE-2026-66046)
* expat: Expat: XML Injection via Malformed UTF-16 Input (CVE-2026-93990)
For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
Fixed packages 2
| Release | Package | Fixed in |
|---|---|---|
| AlmaLinux · 8 | expat | 2.5.0-4.el8_10 |
| AlmaLinux · 8 | expat-devel | 2.5.0-4.el8_10 |
Vulnerabilities 2
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High 7.5
Expat Denial of Service via storeAtts() Quadratic Complexity
Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementTy…
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High 7.5
Expat before 2.8.5 Malformed UTF-16 Acceptance via Unchecked Surrogate
Expat before 2.8.5 fails to validate that a high surrogate in UTF-16 input is followed by a low surrogate, allowing malformed UTF-16 sequences to be accepted. Attackers can supply UTF-16 encoded XML containing lone high surrogates that consume the following c…