Bug 2497046 (CVE-2026-14534) - CVE-2026-14534 fickling: python: fickling: Arbitrary code execution due to incomplete denylist in deserialization
Summary: CVE-2026-14534 fickling: python: fickling: Arbitrary code execution due to in...
Keywords:
Status: NEW
Alias: CVE-2026-14534
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
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Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-07-04 14:01 UTC by OSIDB Bzimport
Modified: 2026-08-20 20:29 UTC (History)
1 user (show)

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Description OSIDB Bzimport 2026-07-04 14:01:20 UTC
Trail of Bits fickling versions up to and including 0.1.10 do not include the Python standard library modules _posixsubprocess, site, and atexit in the UNSAFE_IMPORTS denylist (fickle.py). Because these modules are absent from the denylist, fickling's check_safety() function returns LIKELY_SAFE with zero findings for pickle payloads that invoke dangerous functions including _posixsubprocess.fork_exec (C-level process spawner capable of executing arbitrary binaries), site.execsitecustomize (executes arbitrary site customization code), and atexit._run_exitfuncs (triggers all registered exit handler callbacks). The fickling.load() API chains check_safety() into pickle.loads() as an explicit security gate; a LIKELY_SAFE verdict causes the payload to be deserialized and executed. This shares the same root cause as CVE-2026-22607 (cProfile), CVE-2025-67748 (pty), and CVE-2025-67747 (marshal/types). OvertlyBadEvals does not flag these modules because they are standard library imports. UnsafeImports does not flag them because they are not in the denylist. The UnusedVariables heuristic is defeated by the SETITEMS opcode pattern.


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