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Low, CVSS 2.3amended

Fickling has a detection bypass via stdlib network-protocol constructors

GHSA-83pf-v6qq-pwmr

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (fickling 0.1.8), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • PyPI fickling

    Affected
    <= 0.1.7
    Fixed in
    0.1.8

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
2.3 · CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N · score source
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

Our assessment imtplib, imaplib, ftplib, poplib, telnetlib, and nntplib were added to the list of unsafe imports (https://github.com/trailofbits/fickling/commit/6d20564d23acf14b42ec883908aed159be7b9ade). The UnusedVariables heuristic works as expected. Original report Summary Fickling's checksafety() API and --check-safety CLI flag incorrectly rate as LIKELYSAFE pickle files that open outbound TCP connections at deserialization time using stdlib network-protocol constructors: smtplib.SMTP, imaplib.IMAP4, ftplib.FTP, poplib.POP3, telnetlib.Telnet, and nntplib.NNTP. The bypass exploits two independent root causes described below. --- Root Cause 1: Incomplete blocklist (fixed in PR #233) fickling/fickle.py (lines 41-97) defines UNSAFEIMPORTS, the primary blocklist. fickling/analysis.py (lines 229-248) defines the parallel UnsafeImportsML.UNSAFEMODULES dict. Both omitted the following stdlib network-protocol modules whose constructors open a TCP socket at instantiation time: | Module |…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-83pf-v6qq-pwmr

  2. Revision 2 · amended ·

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

  3. Revision 1 · created ·

    Published from osv record GHSA-83pf-v6qq-pwmr

Agent brief

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# Patch Next advisory brief: GHSA-83pf-v6qq-pwmr

Advisory: Fickling has a detection bypass via stdlib network-protocol constructors
IDs: GHSA-83pf-v6qq-pwmr
Record: https://patchnext.com/advisories/ghsa-83pf-v6qq-pwmr (revision 3, source checked 26 Oct 2026, 13:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: fickling 0.1.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI fickling: affected <= 0.1.7; fixed in 0.1.8

## 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-83pf-v6qq-pwmr (OSV record GHSA-83pf-v6qq-pwmr lists affected ranges: PyPI fickling >=0 <0.1.8 (fixed))
- Verified: https://github.com/advisories/GHSA-83pf-v6qq-pwmr (GitHub-reviewed advisory GHSA-83pf-v6qq-pwmr lists affected ranges: PyPI fickling >=0 <=0.1.7)

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