CVE-2026-66046

Description

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 elementType->defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options.

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Produits concernés

• libexpat project libexpat

Scores CVSS

Faiblesses (CWE)

• CWE-407

Références

• https://github.com/libexpat/libexpat/pull/1321 ExploitPatchVendor Advisory
• https://www.vulncheck.com/advisories/expat-denial-of-service-via-storeatts-quadratic-complexity ExploitPatchThird Party Advisory

Ailleurs

• NVD
• CVE.org
• CIRCL Vulnerability-Lookup
• CERT-FR
• GitHub Advisories