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Response snapshot Oct 30, 2026, 23:06 UTC

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VulnerabilityCVE-2026-118938

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...

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.

At a glance

Exploited
Not known
Severity
8.8 High (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-118938 (opens a new tab)

What happened

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.

Continue reading

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.

Scores and how they were measured

CVSS base severity

8.8

Version 3.1As of

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Sources

  1. Primary source

    NVD CVE-2026-118938 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 30). 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... (CVE-2026-118938). https://kevwire.com/record/CVE-2026-118938

MLA

"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... (CVE-2026-118938)." KEVWire, 30 Oct. 2026, kevwire.com/record/CVE-2026-118938.

Chicago

KEVWire. "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... (CVE-2026-118938)." Last modified October 30, 2026. https://kevwire.com/record/CVE-2026-118938.

Evidence summary (plain text)

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... (Oct 30, 2026).
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.
CVSS 8.8 (version 3.1; evidence as of Oct 30, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-118938).
Sources:
NVD CVE-2026-118938: https://nvd.nist.gov/vuln/detail/CVE-2026-118938
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T21:30:58.248Z&lastModEndDate=2026-10-30T23:05:57.023Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-30T20:56:01.746Z&lastModEndDate=2026-10-30T22:30:56.395Z&resultsPerPage=500&startIndex=0
Record ID: CVE-2026-118938.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 30, 2026, 23:05 UTC. Ingestion is not an independent editorial investigation.

NVD status: Received. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

Record detail