Fickling has Code Injection vulnerability via pty.spawn()

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.1 · CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P · score source

EPSS

• CVE-2025-67748: 0.27% estimated exploitation activity in the next 30 days; percentile 19.23 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Fickling Assessment Based on the test case provided in the original report below, this bypass was caused by pty missing from our block list of unsafe module imports (as previously documented in #108), rather than the unused variable heuristic. This led to unsafe pickles based on pty.spawn() being incorrectly flagged as LIKELYSAFE, and was fixed in https://github.com/trailofbits/fickling/pull/187. Original report Summary An unsafe deserialization vulnerability in Fickling allows a crafted pickle file to bypass the "unused variable" heuristic, enabling arbitrary code execution. This bypass is achieved by adding a trivial operation to the pickle file that "uses" the otherwise unused variable left on the stack after a malicious operation, tricking the detection mechanism into classifying the file as safe. Details Fickling relies on the heuristic of detecting unused variables in the VM's stack after execution. Opcodes like REDUCE, OBJ, and INST, which can be used for arbitrary code…

Published by the source

15 Dec 2025, 23:37 UTC

Last modified by the source

5 Jun 2026, 18:00 UTC

Source last checked

26 Oct 2026, 13:42 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-r7v6-mfhq-g3m2

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-r7v6-mfhq-g3m2

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# Patch Next advisory brief: CVE-2025-67748

Advisory: Fickling has Code Injection vulnerability via pty.spawn()
IDs: CVE-2025-67748, GHSA-r7v6-mfhq-g3m2
Record: https://patchnext.com/advisories/cve-2025-67748 (revision 3, source checked 26 Oct 2026, 13:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: fickling 0.1.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI fickling: affected < 0.1.6; fixed in 0.1.6

## Suggested inspection (read-only)
- `python -m pip show fickling`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on fickling.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-r7v6-mfhq-g3m2 (OSV record GHSA-r7v6-mfhq-g3m2 lists affected ranges: PyPI fickling >=0 <0.1.6 (fixed))
- Verified: https://github.com/advisories/GHSA-r7v6-mfhq-g3m2 (GitHub-reviewed advisory GHSA-r7v6-mfhq-g3m2 lists affected ranges: PyPI fickling >=0 <0.1.6)

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