Summary
Package updates are available for Amazon Linux 2023 that fix the following vulnerabilities: CVE-2026-21876: The OWASP core rule set (CRS) is a set of generic attack detection rules for use with compatible web application firewalls. Prior to versions 4.22.0 and 3.3.8, the current rule 922110 has a bug when processing multipart requests with multiple parts. When the first rule in a chain iterates over a collection (like `MULTIPART_PART_HEADERS`), the capture variables (`TX:0`, `TX:1`) get overwritten with each iteration. Only the last captured value is available to the chained rule, which means malicious charsets in earlier parts can be missed if a later part has a legitimate charset. Versions 4.22.0 and 3.3.8 patch the issue.
Fixed packages 1
| Release | Package | Fixed in |
|---|---|---|
| Amazon Linux · 2023 | mod_security_crs | 0:4.2.0-1.amzn2023.0.2 |
Vulnerabilities 1
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Critical 9.3
OWASP CRS has multipart bypass using multiple content-type parts
The OWASP core rule set (CRS) is a set of generic attack detection rules for use with compatible web application firewalls. Prior to versions 4.22.0 and 3.3.8, the current rule 922110 has a bug when processing multipart requests with multiple parts. When the …
References
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web
https://alas.aws.amazon.com/cve/html/CVE-2026-21876.html