CVE-2026-14535

Full vulnerability record from the local CVENow database.

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.

Severity

CRITICAL

CVSS score

9.8 (v3.1)

Vulnerability status

Analyzed

Source identifier

aa17e1a1-c329-4d6e-a1ed-8d0188aea082

Published

2026-07-04 14:16:29.063000

Last modified

2026-10-25 15:10:00.147000

View original CVE JSON

{
  "id": "CVE-2026-14535",
  "sourceIdentifier": "aa17e1a1-c329-4d6e-a1ed-8d0188aea082",
  "published": "2026-07-04T14:16:29.063",
  "lastModified": "2026-10-25T15:10:00.147",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "En las versiones de fickling de Trail of Bits hasta la 0.1.11 inclusive, la pasada de análisis UnsafeImportsML llama incondicionalmente a AnalysisContext.shorten_code(node) en cada nodo de importación que inspecciona, independientemente de si la importación está marcada como insegura. Esta llamada registra la representación de código acortada en el conjunto compartido AnalysisContext.reported_shortened_code. Cuando la pasada de análisis MLAllowlist se ejecuta posteriormente, llama al mismo método shorten_code(), recibe already_reported=True para cada importación y ejecuta una sentencia continue que omite completamente su verificación de lista de permitidos. Esto convierte a MLAllowlist en código muerto para todas las importaciones - nunca evalúa si una importación está en la lista de permitidos de ML o no. La pasada MLAllowlist fue diseñada para detectar importaciones de módulos fuera del ecosistema de ML conocido como seguro (torch, numpy, transformers, etc.) que escapan a la lista de denegados de UnsafeImports. Con MLAllowlist inoperativa, cualquier módulo de la biblioteca estándar que no esté en la lista de denegados UNSAFE_IMPORTS puede ser invocado a través de la deserialización de pickle mientras que check_safety() de fickling devuelve LIKELY_SAFE. La API fickling.load() encadena check_safety() en pickle.loads() como una puerta de seguridad explícita, lo que significa que un veredicto LIKELY_SAFE hace que la carga útil sea deserializada y ejecutada. La causa raíz es el estado mutable compartido entre pasadas de análisis independientemente correctas - UnsafeImportsML funciona según lo diseñado de forma aislada, MLAllowlist funciona según lo diseñado de forma aislada, pero el conjunto compartido reported_shortened_code hace que UnsafeImportsML envenene la lógica de deduplicación de MLAllowlist."
    }
  ],
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      "affectedData": [
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          "defaultStatus": "unaffected",
          "collectionURL": "https://pypi.org/project/fickling/",
          "packageName": "fickling",
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          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "REQUIRED",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
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      "url": "https://github.com/trailofbits/fickling/commit/41ce7cb01edd97072994039574a2301ebb3f463d",
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