Trail of Bits fickling versions up to 0.1.12 contain a vulnerability where a pickle STACK_GLOBAL operand with a dotted __qualname__ is incorrectly resolved to an arbitrary attribute path instead of a module-level function. This flaw allows an attacker to execute arbitrary code by loading a crafted pickle that reaches the optparse.Values.read_file method, which executes code from a file. The vulnerability bypasses fickling's safety checks because the trailing attribute reference is not analyzed or flagged. The issue remains unpatched as of the latest vendor commit on 2026-10-30.