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Algorithmic Complexity The advisory has been revoked - it doesn't affect any version of package expat-devel  (opens in a new tab)

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EPSS
0.74% (53rd percentile)

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  • Snyk IDSNYK-RHEL10-EXPATDEVEL-19836189
  • published16 Sept 2026
  • disclosed18 Aug 2026
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Introduced: 18 Aug 2026

CVE-2026-66046  (opens in a new tab)
CWE-407  (opens in a new tab)

Amendment

The Red Hat security team deemed this advisory irrelevant for RHEL:10.

NVD Description

Note: Versions mentioned in the description apply only to the upstream expat-devel package and not the expat-devel package as distributed by RHEL.

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.