CVE-2026-21876
Jan. 8, 2026, 6:08 p.m.
9.3
Critical
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.
Product(s) Impacted
| Vendor | Product | Versions |
|---|---|---|
| Owasp |
|
|
Weaknesses
Common security weaknesses mapped to this vulnerability.
CWE-794
Incomplete Filtering of Multiple Instances of Special Elements
The product receives data from an upstream component, but does not filter all instances of a special element before sending it to a downstream component.
*CPE(s)
Affected systems and software identified for this CVE.
| Type | Vendor | Product | Version | Update | Edition | Language | Software Edition | Target Software | Target Hardware | Other Information |
|---|---|---|---|---|---|---|---|---|---|---|
| a | owasp | core_rule_set | <4.22.0 | / | / | / | / | / | / | / |
| a | owasp | core_rule_set | <3.3.8 | / | / | / | / | / | / | / |
References
Tags
CVSS Score
CVSS Data - 3.1
- Attack Vector: NETWORK
- Attack Complexity: LOW
- Privileges Required: NONE
- Scope: CHANGED
- Confidentiality Impact: HIGH
- Integrity Impact: LOW
- Availability Impact: NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
Timeline
Published: Jan. 8, 2026, 2:15 p.m.
Last Modified: Jan. 8, 2026, 6:08 p.m.
Last Modified: Jan. 8, 2026, 6:08 p.m.
Status : Awaiting Analysis
CVE has been recently published to the CVE List and has been received by the NVD.
More infoSource
*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.