Debian dla-4488 : modsecurity-crs - security update

critical Nessus Plugin ID 299744

Synopsis

The remote Debian host is missing one or more security-related updates.

Description

The remote Debian 11 host has a package installed that is affected by multiple vulnerabilities as referenced in the dla-4488 advisory.

------------------------------------------------------------------------- Debian LTS Advisory DLA-4488-1 [email protected] https://www.debian.org/lts/security/ Tobias Frost February 22, 2026 https://wiki.debian.org/LTS
-------------------------------------------------------------------------

Package : modsecurity-crs Version : 3.3.4-1~deb11u2 CVE ID : CVE-2023-38199 CVE-2026-21876 Debian Bug : 1041109 1125084

Multiple issues have been fixed in modsecurity-crs, a set of generic attack detection rules for use with ModSecurity.

CVE-2023-38199

Coreruleset (aka OWASP ModSecurity Core Rule Set) through 3.3.4 does not detect multiple Content-Type request headers on some platforms. This might allow attackers to bypass a WAF with a crafted payload, aka Content-Type confusion between the WAF and the backend application.
This occurs when the web application relies on only the last Content-Type header. Other platforms may reject the additional Content-Type header or merge conflicting headers, leading to detection as a malformed header.

CVE-2026-21876

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.

For Debian 11 bullseye, these problems have been fixed in version 3.3.4-1~deb11u2.

We recommend that you upgrade your modsecurity-crs packages.

For the detailed security status of modsecurity-crs please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/modsecurity-crs

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS Attachment:
signature.asc Description: PGP signature

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Upgrade the modsecurity-crs packages.

Plugin Details

Severity: Critical

ID: 299744

File Name: debian_DLA-4488.nasl

Version: 1.1

Type: local

Agent: unix

Family: Debian Local Security Checks

Published: 2/22/2026

Updated: 2/22/2026

Supported Sensors: Continuous Assessment, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.9

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2023-38199

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.8

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:debian:debian_linux:11.0, p-cpe:/a:debian:debian_linux:modsecurity-crs

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 2/22/2026

Vulnerability Publication Date: 7/13/2023

Reference Information

CVE: CVE-2023-38199, CVE-2026-21876

Detections

Analytics