CVE-2025-34451 Details

A stack-based buffer overflow vulnerability has been identified in rofl0r/proxychains-ng versions through 4.17, prior to commit cc005b7. The issue resides in the function proxy_from_string() within src/libproxychains.c. The vulnerability arises from a missing bounds check when parsing proxy configuration entries that contain excessively long username or password fields. This oversight allows the application to write beyond the limits of fixed-size stack buffers, resulting in memory corruption or crashes. Consequently, the vulnerability can cause a denial-of-service condition and, under certain circumstances, may be exploited further, depending on the execution environment and existing mitigations.

Users can upgrade to version 4.17 or later, or apply the patch available in commit cc005b7. If maintaining a packaged distribution that cannot immediately upgrade, the patch can be backported by applying the single-line change in src/libproxychains.c, removing the proxy type condition from the bounds check.