CVE-2026-14535 Fickling MLAllowlist analysis pass rendered inoperative by shared mutable state in AnalysisContext.shorten_code()
Shared mutable state disables the ML allowlist check, allowing arbitrary code execution via pickle deserialization of standard library modules.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-14535?
CVE-2026-14535 is a high-severity unsafe deserialization vulnerability in trailofbits fickling, published on 4 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
In Trail of Bits fickling versions up to and including 0.1.11, the UnsafeImportsML analysis pass unconditionally calls AnalysisContext.shorten_code(node) on every import node it inspects, regardless of whether the import is flagged as unsafe. This call registers the shortened code representation in the shared AnalysisContext.reported_shortened_code set. When the MLAllowlist analysis pass subsequently runs, it calls the same shorten_code() method, receives already_reported=True for every import, and executes a continue statement that skips its allowlist check entirely. This renders MLAllowlist dead code for all imports — it never evaluates whether an import is in the ML allowlist or not. The MLAllowlist pass was designed to catch imports of modules outside the known-safe ML ecosystem (torch, numpy, transformers, etc.) that slip past the UnsafeImports denylist. With MLAllowlist inoperative, any standard library module not in the UNSAFE_IMPORTS denylist can be invoked via pickle deserialization while fickling's check_safety() returns LIKELY_SAFE. The fickling.load() API chains check_safety() into pickle.loads() as an explicit security gate, meaning a LIKELY_SAFE verdict causes the payload to be deserialized and executed. The root cause is shared mutable state between independently-correct analysis passes — UnsafeImportsML works as designed in isolation, MLAllowlist works as designed in isolation, but the shared reported_shortened_code set causes UnsafeImportsML to poison MLAllowlist's deduplication logic.
Weakness: CWE-693
Which versions are affected by CVE-2026-14535?
1 open source package ship an affected version, including fickling. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
fickling PyPI | All versions | 0.1.12 |
Products include Trailofbits Fickling.
How do I fix CVE-2026-14535?
Upgrade fickling to 0.1.12 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-14535 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-14535 exists.
Other vulnerabilities in trailofbits fickling
- CVE-2026-22606 Fickling has a bypass via runpy.run_path() and runpy.run_module()
- CVE-2026-22607 Fickling Blocklist Bypass: cProfile.run()
- CVE-2026-22608 Fickling vulnerable to use of ctypes and pydoc gadget chain to bypass detection
- CVE-2026-22609 Fickling has Static Analysis Bypass via Incomplete Dangerous Module Blocklist
- CVE-2026-22612 Fickling vulnerable to detection bypass due to "builtins" blindness
Sources
Also known as GHSA-cffv-grgg-g429, GHSA-mgx3-9w7v-8674, PYSEC-2026-2150.