CVE-2026-42536
Description
A flaw was found in Apache HTTP Server, specifically within the mod_xml2enc module. This heap-based buffer overflow vulnerability can be triggered when processing untrusted content through the xml2StartParse function. A remote attacker could potentially exploit this to cause a denial of service, information disclosure, or possibly arbitrary code execution.
Statement
In Red Hat Enterprise Linux (RHEL), the httpd package includes mod_xml2enc, which provides encoding support for filters like mod_proxy_html. Because this flaw relies on processing unvetted or untrusted input text lengths, the impact presents a high risk to availability (Denial of Service via worker crashes) and a potential risk to confidentiality if an attacker is capable of executing remote code within the context of the apache or httpd daemon process.
Mitigation
To mitigate this vulnerability, disable the `mod_xml2enc` module if its functionality for XML internationalization is not essential. This can be done by commenting out the `LoadModule xml2enc_module modules/mod_xml2enc.so` directive in the Apache HTTP Server configuration. A service restart is required for the change to take effect.
bash
# Edit the Apache configuration file, e.g., /etc/httpd/conf.modules.d/00-base.conf
# Comment out the line:
# LoadModule xml2enc_module modules/mod_xml2enc.so
# Reload the httpd service
sudo systemctl reload httpd
*Note: Disabling `mod_xml2enc` will cause any configurations relying heavily on `mod_proxy_html` or raw HTML/XML encoding conversions to function incorrectly or fail. Red Hat strongly recommends upgrading to a patched version of `httpd` as soon as it becomes available for your specific RHEL channel.*
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of the product's implicit security policy. This can often be used to subvert any other security service.
Availability
Technical Impact: Modify Memory; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)
Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the product into an infinite loop.
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