trailofbits fickling up to 0.1.11 shorten_code protection mechanism

Summaryinfo

A vulnerability, which was classified as critical, was found in trailofbits fickling up to 0.1.11. This issue affects the function shorten_code. Executing a manipulation can lead to protection mechanism. This vulnerability is handled as CVE-2026-14535. The attack can be executed remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in trailofbits fickling up to 0.1.11. This vulnerability affects the function shorten_code. The manipulation with an unknown input leads to a protection mechanism vulnerability. The CWE definition for the vulnerability is CWE-693. The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The weakness was released with Bombadil Systems LLC as GHSA-cffv-grgg-g429. The advisory is shared for download at github.com. This vulnerability was named CVE-2026-14535 since 07/03/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available.

Upgrading to version 0.1.12 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 41ce7cb01edd97072994039574a2301ebb3f463d is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-41676). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Application Server Software

Vendor

• trailofbits

Name

• fickling

Version

• 0.1.0
• 0.1.1
• 0.1.2
• 0.1.3
• 0.1.4
• 0.1.5
• 0.1.6
• 0.1.7
• 0.1.8
• 0.1.9
• 0.1.10
• 0.1.11

License

• open-source

Website

• Product: https://github.com/trailofbits/fickling/

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Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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