CVE-2026-21876
CRITICAL 9.3EPSS 13.6%
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.
- CVSS v3.1
- 5.3 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - CVSS v3.1
- 9.3 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N - EPSS
- 13.63% chance of exploitation in the next 30 days, 96th percentile
- Published
- 2026-01-08
- Updated
- 2026-04-09
Proof-of-concept exploits (3)
- Mefhika120/CVE-2026-218760★ · 2026-01-09
- CVEs-Labs/CVE-2026-218760★ · 2026-04-22
- daytriftnewgen/CVE-2026-218760★ · 2026-06-19