What’s Vulnerable › Vulnerabilities

CVE-2025-54812: Apache Log4cxx: Improper HTML escaping in HTMLLayout

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-08-22 · updated 2026-06-17
• Weakness: CWE-117

Description

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.

Affected products

• Apache Software Foundation Apache Log4cxx: before 1.5.0 — fixed in 1.5.0

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache Log4cxx 1.5.0. Check the vendor advisory for mitigations.

References

• https://github.com/apache/logging-log4cxx/pull/509
• https://github.com/apache/logging-log4cxx/pull/514
• https://logging.apache.org/security.html#CVE-2025-54812
• http://www.openwall.com/lists/oss-security/2025/08/22/2
• https://lists.debian.org/debian-lts-announce/2025/10/msg00002.html

Get alerted when CVE-2025-54812 or the next vulnerability affects your stack