9.8
CRITICAL CVSS 3.1
CVE-2026-14535
Fickling MLAllowlist analysis pass rendered inoperative by shared mutable state in AnalysisContext.shorten_code()
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.

INFO

Published Date :

July 4, 2026, 2:16 p.m.

Last Modified :

July 10, 2026, 3 p.m.

Remotely Exploit :

Yes !

Source :

aa17e1a1-c329-4d6e-a1ed-8d0188aea082
Affected Products

The following products are affected by CVE-2026-14535 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Trailofbits fickling
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 134c704f-9b21-4f2e-91b3-4a467353bcc0
CVSS 3.1 HIGH aa17e1a1-c329-4d6e-a1ed-8d0188aea082
CVSS 3.1 CRITICAL [email protected]
Solution
Update the library to fix the analysis pass interaction and prevent incorrect safety assessments.
  • Update the fickling library to a version later than 0.1.11.
  • Verify analysis passes interact correctly after the update.
  • Ensure allowlist checks are performed for all imports.
  • Review code for unexpected safe import verdicts.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-14535.

URL Resource
https://github.com/trailofbits/fickling/commit/41ce7cb01edd97072994039574a2301ebb3f463d Patch
https://github.com/trailofbits/fickling/pull/278 Issue Tracking Patch
https://github.com/trailofbits/fickling/releases/tag/v0.1.12 Release Notes
https://github.com/trailofbits/fickling/security/advisories/GHSA-cffv-grgg-g429 Exploit Third Party Advisory
https://github.com/trailofbits/fickling/security/advisories/GHSA-cffv-grgg-g429 Exploit Third Party Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-14535 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-14535 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-14535 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2026-14535 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Jul. 10, 2026

    Action Type Old Value New Value
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    Added CPE Configuration OR *cpe:2.3:a:trailofbits:fickling:*:*:*:*:*:python:*:* versions up to (including) 0.1.11
    Added Reference Type CISA-ADP: https://github.com/trailofbits/fickling/security/advisories/GHSA-cffv-grgg-g429 Types: Exploit, Third Party Advisory
    Added Reference Type BombadilSystems: https://github.com/trailofbits/fickling/commit/41ce7cb01edd97072994039574a2301ebb3f463d Types: Patch
    Added Reference Type BombadilSystems: https://github.com/trailofbits/fickling/pull/278 Types: Issue Tracking, Patch
    Added Reference Type BombadilSystems: https://github.com/trailofbits/fickling/releases/tag/v0.1.12 Types: Release Notes
    Added Reference Type BombadilSystems: https://github.com/trailofbits/fickling/security/advisories/GHSA-cffv-grgg-g429 Types: Exploit, Third Party Advisory
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Jul. 06, 2026

    Action Type Old Value New Value
    Added Reference https://github.com/trailofbits/fickling/security/advisories/GHSA-cffv-grgg-g429
    Added SSVC {'id': 'CVE-2026-14535', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-07-06T14:58:30.612222Z'}
  • New CVE Received by aa17e1a1-c329-4d6e-a1ed-8d0188aea082

    Jul. 04, 2026

    Action Type Old Value New Value
    Added Affected [{'vendor': 'trailofbits', 'product': 'fickling', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'custom', 'lessThanOrEqual': '0.1.11'}, {'status': 'unaffected', 'version': '0.1.12', 'versionType': 'custom'}], 'packageName': 'fickling', 'collectionURL': 'https://pypi.org/project/fickling/', 'defaultStatus': 'unaffected'}]
    Added 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.
    Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
    Added CWE CWE-693
    Added Reference https://github.com/trailofbits/fickling/commit/41ce7cb01edd97072994039574a2301ebb3f463d
    Added Reference https://github.com/trailofbits/fickling/pull/278
    Added Reference https://github.com/trailofbits/fickling/releases/tag/v0.1.12
    Added Reference https://github.com/trailofbits/fickling/security/advisories/GHSA-cffv-grgg-g429
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.