CVE-2026-21876

Severity CVSS v4.0:

Pending analysis

Type:

Unavailable / Other

Publication date:

08/01/2026

Last modified:

08/01/2026

Description

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.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 9.30 CRITICAL
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Changed
Confidentiality (C): High
Integrity (I): Low
Availability (A): None

Base Score 3.x

9.30

Severity 3.x

CRITICAL

CVE-2026-21876

Description

Impact

References to Advisories, Solutions, and Tools