CVE-2026-52747
Description
A flaw was found in ModSecurity, an open-source web application firewall (WAF). The multipart/form-data request body parser in libmodsecurity incorrectly handles embedded line breaks in non-file form-field values. This discrepancy between ModSecurity and backend applications, which preserve line breaks, can allow an attacker to bypass security rules. This bypass could lead to the execution of dangerous payloads that rely on line breaks, potentially resulting in a security compromise.
Statement
This issue is classified as Moderate severity primarily because: Conditions for Exploitation: Successful exploitation requires a specific scenario where the backend application preserves line breaks and is inherently vulnerable to a payload that utilizes those line breaks.
Additionally, the ModSecurity configuration must rely on rules inspecting the affected ARGS or ARGS_POST variables to allow the bypass to occur.
Impact Limitations: The vulnerability functions solely as a security control bypass, allowing potentially malicious requests to evade the Web Application Firewall (WAF). It does not directly cause privilege escalation, data corruption, or arbitrary code execution on the host system. The actual impact depends entirely on whether the backend application being protected is vulnerable to the bypassed requests.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.8 | 8.6 | 8.6 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Changed | Changed | Changed |
| Confidentiality | None | None | None |
| Integrity Impact | Low | High | High |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
Understanding the Weakness (CWE)
Access Control,Integrity
Technical Impact: Bypass Protection Mechanism; Execute Unauthorized Code or Commands
An attacker could include dangerous input that bypasses validation protection mechanisms which can be used to launch various attacks including injection attacks, execute arbitrary code or cause other unintended behavior.
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