Summary
Package updates are available for Amazon Linux 2 that fix the following vulnerabilities: CVE-2026-66046: 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.
Fixed packages 4
| Release | Package | Fixed in |
|---|---|---|
| Amazon Linux · 2 | expat | 0:2.1.0-15.amzn2.0.9 |
| Amazon Linux · 2 | expat-debuginfo | 0:2.1.0-15.amzn2.0.9 |
| Amazon Linux · 2 | expat-devel | 0:2.1.0-15.amzn2.0.9 |
| Amazon Linux · 2 | expat-static | 0:2.1.0-15.amzn2.0.9 |
Vulnerabilities 1
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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…
References
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web
https://alas.aws.amazon.com/cve/html/CVE-2026-66046.html