CVE catalog
CVE-2026-21876
modsecurity-crs: CVE-2026-21876
- Severity
- Medium
- Published
- Source
- [NVD] · [CVE record]
- EPSS
- 17.88% · Oct 25, 2026
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.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | modsecurity-crs | sid | 3.3.9-1 | fixed |
| Debian | modsecurity-crs | forky | 3.3.9-1 | fixed |
| Debian | modsecurity-crs | trixie | 3.3.7-1+deb13u2 | fixed |
| Debian | modsecurity-crs | trixie-security | 3.3.7-1+deb13u1 | fixed |
| Debian | modsecurity-crs | bookworm | 3.3.4-1+deb12u3 | fixed |
| Debian | modsecurity-crs | bookworm-security | 3.3.4-1+deb12u1 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | modsecurity-crs | source | sid | 3.3.8-1 | not yet assigned | Not reported | [1125084] |
| Debian | modsecurity-crs | source | forky | 3.3.8-1 | not yet assigned | Not reported | [1125084] |
| Debian | modsecurity-crs | source | trixie | 3.3.7-1+deb13u1 | not yet assigned | Not reported | [1125084] |
| Debian | modsecurity-crs | source | bookworm | 3.3.4-1+deb12u1 | not yet assigned | Not reported | [1125084] |
OpenFactory catalog packages
[Debian 12 (Bookworm)]
- [modsecurity-crs]Fixed
Details (4)
3.3.4-1+deb12u3· all · bookwormFixed · Fixed:
3.3.4-1+deb12u1dsa · modsecurity-crs · debian · bookworm; dsa · modsecurity-crs · debian · 12
3.3.4-1+deb12u3· all · bookwormFixed · Fixed:
3.3.4-1+deb12u1dsa · modsecurity-crs · debian · bookworm; dsa · modsecurity-crs · debian · 12
3.3.4-1+deb12u1· all · bookworm-securityFixed · Fixed:
3.3.4-1+deb12u1dsa · modsecurity-crs · debian · bookworm; dsa · modsecurity-crs · debian · 12
3.3.4-1+deb12u1· all · bookworm-securityFixed · Fixed:
3.3.4-1+deb12u1dsa · modsecurity-crs · debian · bookworm; dsa · modsecurity-crs · debian · 12
[Debian 13 (Trixie)]
- [modsecurity-crs]Fixed
Details (4)
3.3.7-1+deb13u2· all · trixieFixed · Fixed:
3.3.7-1+deb13u1dsa · modsecurity-crs · debian · 13
3.3.7-1+deb13u2· all · trixieFixed · Fixed:
3.3.7-1+deb13u1dsa · modsecurity-crs · debian · 13
3.3.7-1+deb13u1· all · trixie-securityFixed · Fixed:
3.3.7-1+deb13u1dsa · modsecurity-crs · debian · 13
3.3.7-1+deb13u1· all · trixie-securityFixed · Fixed:
3.3.7-1+deb13u1dsa · modsecurity-crs · debian · 13
Observed:
References
- [https://osv.dev/vulnerability/DEBIAN-CVE-2026-21876]
- [https://osv.dev/vulnerability/DSA-6105-1]
- [https://security-tracker.debian.org/tracker/CVE-2026-21876]
- [https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-1185.json]
[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database]