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High ALAS2023-2026-1399 1 CVE

Important: mod_security_crs security update (Amazon Linux 2023)

Published Feb 5, 2026 · Updated Feb 5, 2026

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

ReleasePackageFixed in
Amazon Linux · 2023 mod_security_crs 0:4.2.0-1.amzn2023.0.2

Vulnerabilities 1

  • Critical 9.3
    CVE-2026-21876 Public exploit EPSS 17%

    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

  • web
    https://alas.aws.amazon.com/cve/html/CVE-2026-21876.html