9fans plan9port Null Pointer Dereference Vulnerability in X.509 Value Decode Function

A null pointer dereference vulnerability has been identified in 9fans plan9port versions prior to commit 9da5b44. The issue arises in the X.509 value_decode function within the library src/libsec/port/x509.c. This vulnerability requires local access to exploit and has been publicly disclosed, with an available proof-of-concept exploit.

Impact

Exploitation of this vulnerability leads to a segmentation fault, causing a denial-of-service condition by crashing the application.

Reproduction

The vulnerability can be reproduced by compiling the plan9port source code with Clang, using AddressSanitizer to detect memory errors. After applying a fuzzing harness that targets the value_decode function, the application can be run with a crafted input that triggers the null pointer dereference.

Remediation

Users are advised to update to the latest version of plan9port, which includes the patch for this vulnerability.