Apache Log4cxx up to 1.4.x HTMLLayout HTML injection

Summaryinfo

A vulnerability, which was classified as problematic, was found in Apache Log4cxx up to 1.4.x. This vulnerability affects unknown code of the component HTMLLayout. Executing a manipulation can lead to HTML injection. This vulnerability appears as CVE-2025-54812. The attack may be performed from remote. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Apache Log4cxx up to 1.4.x. This vulnerability affects some unknown functionality of the component HTMLLayout. The manipulation with an unknown input leads to a html injection vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. CVE summarizes:

Improper Output Neutralization for Logs vulnerability in Apache Log4cxx. When using HTMLLayout, logger names are not properly escaped when writing out to the HTML file. If untrusted data is used to retrieve the name of a logger, an attacker could theoretically inject HTML or Javascript in order to hide information from logs or steal data from the user. In order to activate this, the following sequence must occur: * Log4cxx is configured to use HTMLLayout. * Logger name comes from an untrusted string * Logger with compromised name logs a message * User opens the generated HTML log file in their browser, leading to potential XSS Because logger names are generally constant strings, we assess the impact to users as LOW This issue affects Apache Log4cxx: before 1.5.0. Users are recommended to upgrade to version 1.5.0, which fixes the issue.

The advisory is shared for download at logging.apache.org. This vulnerability was named CVE-2025-54812 since 07/30/2025. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 11/03/2025). The MITRE ATT&CK project declares the attack technique as T1059.007.

The vulnerability scanner Nessus provides a plugin with the ID 266592 (Debian dla-4322 : liblog4cxx-dev - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.5.0 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (266592) and EUVD (EUVD-2025-25621). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• Apache

Name

• Log4cxx

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4

License

• open-source

Website

• Vendor: https://www.apache.org/

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Once again VulDB remains the best source for vulnerability data.

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