Natural Language Toolkit (NLTK) has path traversal in FramenetCorpusReader.frame() that allows arbitrary XML file read, bypassing the nltk.pathsec sandbox (ENFORCE=True)

Exploitation

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

CVSS

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

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

Summary FramenetCorpusReader.frame(name) interpolates a caller-supplied frame name into an XML file path that is read with the builtin open(), bypassing CorpusReader.open() and the nltk.pathsec sandbox — including strict ENFORCE=True mode. A ../ sequence in the name escapes the corpus root, yielding an arbitrary XML file read whose parsed content is returned to the caller. Details framebyname builds the path by joining the corpus root, the frame directory, and the caller-supplied name with a fixed .xml extension, with no containment check, then constructs an XMLCorpusView from that string path. Because the view is built from a string rather than a PathPointer, it reads with the builtin open(), so nltk.pathsec.validatepath() is never invoked and ENFORCE=True does not block the access. This is the same path-traversal class previously hardened for the generic corpus readers; framebyname never goes through CorpusReader.open(), so that protection does not apply. The same…

Published by the source

31 Jul 2026, 16:50 UTC

Last modified by the source

31 Jul 2026, 16:50 UTC

Source last checked

26 Oct 2026, 13:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xh95-f55m-82fw

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# Patch Next advisory brief: CVE-2026-12074

Advisory: Natural Language Toolkit (NLTK) has path traversal in FramenetCorpusReader.frame() that allows arbitrary XML file read, bypassing the nltk.pathsec sandbox (ENFORCE=True)
IDs: CVE-2026-12074, GHSA-xh95-f55m-82fw
Record: https://patchnext.com/advisories/cve-2026-12074 (revision 1, source checked 26 Oct 2026, 13:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nltk 3.10.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI nltk: affected <= 3.9.4; fixed in 3.10.0

## Suggested inspection (read-only)
- `python -m pip show nltk`: 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 nltk.
- 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://github.com/advisories/GHSA-xh95-f55m-82fw (GitHub-reviewed advisory GHSA-xh95-f55m-82fw lists affected ranges: PyPI nltk >=0 <=3.9.4)

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