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Fencer Vulns
high 8.8

CVE-2026-118938 json

Fickling check_safety() bypass: dotted __qualname__ in STACK_GLOBAL resolves a class-method attribute path that evades call analysis

published 2026-10-30 9 d ago modified 2026-11-06 2 d ago also EUVD-2026-114515

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

In Trail of Bits fickling through 0.1.12, a pickle STACK_GLOBAL operand carrying a dotted __qualname__ (for example "Values.read_file") is resolved by pickle's find_class through _getattribute to an arbitrary attribute path rather than to a module-level function. Fickling records only the leading component of the name in its import tracking and renders the operation as a plain import (for instance, 'python -m fickling' displays it as 'from optparse import Values.read_file'), so the trailing attribute reference is never analyzed as a call. The OvertlyBadEvals analysis pass does not flag it, and check_safety() returns LIKELY_SAFE with zero findings. This allows an attacker to reach a class method that performs code execution: optparse.Values.read_file executes exec(open(filename).read(), vars), achieving arbitrary code execution when the crafted pickle is loaded through fickling.load(), which chains check_safety() into pickle.loads() as an explicit security gate. optparse is present in all current CPython 3.x releases (deprecated as of Python 3.13, not removed). This weakness is in the resolution and analysis of dotted attribute-path names, and is distinct from and independently fixable from the module-origin trust weakness tracked as CVE-2026-16760: resolving or flagging dotted attribute-path imports closes this vector while leaving the module-level trust behavior unchanged. This bypass was verified to remain present on the vendor master branch at commit d011709 as of 2026-10-30, after the vendor's October blocklist additions and a new heuristic that flags private stdlib attributes; because the public class method Values.read_file is neither blocklisted nor flagged as a private attribute, it is not addressed by those remediations.

Patch / fix

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-118938 updated cvss 7.8

fickling: fickling: Arbitrary code execution via safety analysis bypass for dotted attribute paths

  • Red Hat OpenShift AI (RHOAI) rhoai/odh-th-torch-cpu-py312-rhel9, rhoai/odh-th-torch-cuda-py312-rhel9
    affected: workaround, no fix available

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2 d ago

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

  • trailofbits fickling

Classification

Weakness
  • CWE-706 Use of Incorrectly-Resolved Name or Reference
  • CWE-502 Deserialization of Untrusted Data

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.