CVE-2026-14534: 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 th...

Description

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.

Metrics

CVSS 3.1

8.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS Probability

0.33%

24.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Trailofbits	Fickling	<= 0.1.10

References

https://github.com/trailofbits/fickling/commit/e8408615b63adf034f891f653692ab9b51f0f5afPatch
https://github.com/trailofbits/fickling/pull/272Issue Tracking, Patch
https://github.com/trailofbits/fickling/releases/tag/v0.1.11Release Notes
https://github.com/trailofbits/fickling/security/advisories/GHSA-m6fh-58r7-x697Exploit, Vendor Advisory
https://github.com/trailofbits/fickling/security/advisories/GHSA-m6fh-58r7-x697Exploit, Vendor Advisory

Timeline

Published: Jul 4, 2026
Last Modified: Jul 10, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-14534?

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.

How severe is CVE-2026-14534?

CVE-2026-14534 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 0.33% probability of exploitation in the next 30 days.

How do I fix CVE-2026-14534?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Related CVEs from 2026

View all 2026CVEs →