CVE-2025-49506 Apache Portable Runtime Utility Password Validation Timing Attack

The Apache Portable Runtime (APR) Utility library, specifically the apr_password_validate function, contains a security flaw tracked as CVE-2025-49506. This vulnerability arises because the library performs password string comparisons in a non-constant time manner. This behavior enables an attacker to perform a timing side-channel attack, measuring the time taken for authentication attempts to deduce valid password information. Because APR is a foundational library used by many web servers and cross-platform applications, the potential impact spans across multiple environments that rely on this library for credential verification. Defenders should prioritize auditing applications that link against vulnerable versions of APR and apply available vendor patches as they are released by package maintainers and upstream sources.

Impact

Successful exploitation of this timing side-channel allows attackers to gain unauthorized information about password validity, potentially facilitating account enumeration or brute-force credential recovery. The scope of potential victims includes any system or application utilizing the APR Utility library for authentication, which is prevalent in enterprise environments across web server configurations and custom software.

Recommendation

• Monitor upstream security bulletins for patched versions of the Apache Portable Runtime (APR) library.
• Update affected services and applications that bundle or dynamically link against vulnerable versions of libaprutil.
• Audit applications that expose authentication endpoints using APR to determine if they are configured to introduce sufficient jitter or rate limiting to mitigate the timing leakage until patches are applied.