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Critical, CVSS 9.3amended

NLTK: JVM argument injection bypass via per-call options in the NLTK Stanford wrappers (incomplete fix of CVE-2026-12841)

CVE-2026-79675GHSA-m4rf-3fr8-xwx3

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (nltk 3.10.3), 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 nltk

    Affected
    <= 3.10.2
    Fixed in
    3.10.3

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
9.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-79675: 0.78% estimated exploitation activity in the next 30 days; percentile 55.83 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Vulnerability The fix for CVE-2026-12841 (CWE-88, JVM argument injection) added validatejavaoptions() to block dangerous JVM flags such as -agentlib, -agentpath, -javaagent, -Xrunjdwp, and @argfile references. However, the validation is only applied when setting global options via configjava(). The java() function's per-call options parameter -- added by PR #3683 (CVE-2026-12615 fix) -- passes options directly to subprocess.Popen without calling validatejavaoptions(). All four Stanford Java wrapper classes accept user-supplied javaoptions and route them through the unvalidated per-call path, bypassing the CVE-2026-12841 fix entirely. Root Cause In nltk/internals.py, the java() function (line 128) accepts an options keyword argument. When options is not None, it is converted to a list and prepended to the JVM command (lines 211-217) without any validation: Compare with configjava() (line 92) which does validate: The four affected wrapper classes store user-supplied javaoptions without…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-m4rf-3fr8-xwx3

  2. Revision 3 · amended ·

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

  3. Revision 2 · amended ·

    Amended from osv record GHSA-m4rf-3fr8-xwx3

  4. Revision 1 · created ·

    Published from ghsa record GHSA-m4rf-3fr8-xwx3

Agent brief

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# Patch Next advisory brief: CVE-2026-79675

Advisory: NLTK: JVM argument injection bypass via per-call options in the NLTK Stanford wrappers (incomplete fix of CVE-2026-12841)
IDs: CVE-2026-79675, GHSA-m4rf-3fr8-xwx3
Record: https://patchnext.com/advisories/cve-2026-79675 (revision 4, source checked 26 Oct 2026, 13:51 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nltk 3.10.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI nltk: affected <= 3.10.2; fixed in 3.10.3

## 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-m4rf-3fr8-xwx3 (GitHub-reviewed advisory GHSA-m4rf-3fr8-xwx3 lists affected ranges: PyPI nltk >=0 <=3.10.2)
- Verified: https://osv.dev/vulnerability/GHSA-m4rf-3fr8-xwx3 (OSV record GHSA-m4rf-3fr8-xwx3 lists affected ranges: PyPI nltk >=0 <3.10.3 (fixed))

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