What’s Vulnerable › Vulnerabilities

CVE-2024-47252: Apache HTTP Server: mod_ssl error log variable escaping

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-07-10 · updated 2026-06-17
• Weakness: CWE-150

Description

Insufficient escaping of user-supplied data in mod_ssl in Apache HTTP Server 2.4.63 and earlier allows an untrusted SSL/TLS client to insert escape characters into log files in some configurations. In a logging configuration where CustomLog is used with "%{varname}x" or "%{varname}c" to log variables provided by mod_ssl such as SSL_TLS_SNI, no escaping is performed by either mod_log_config or mod_ssl and unsanitized data provided by the client may appear in log files.

Affected products

• Apache HTTP Server: from 2.4.0 before 2.4.64 — fixed in 2.4.64

How to fix

Upgrade to a fixed version: Apache HTTP Server 2.4.64. Check the vendor advisory for mitigations.

References

• https://httpd.apache.org/security/vulnerabilities_24.html
• http://www.openwall.com/lists/oss-security/2025/07/10/2
• http://www.openwall.com/lists/oss-security/2025/07/10/6
• https://lists.debian.org/debian-lts-announce/2025/08/msg00009.html

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