vulnerability / NVI-00014164 / Revision 2
NLTK: JVM argument injection bypass via per-call options in the NLTK Stanford wrappers (incomplete fix of CVE-2026-12841)
GitHub lists this reviewed advisory for nltk. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
9.8 critical
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
0.775%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.55832. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
nltk
source listed<= 3.10.2
## Vulnerability The fix for CVE-2026-12841 (CWE-88, JVM argument injection) added `_validate_java_options()` 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 `config_java()`. The `java()` function's per-call `options` parameter -- added by PR #3683 (CVE-2026-12615 fix) -- passes options directly to `subprocess.Popen` without calling `_validate_java_options()`. All four Stanford Java wrapper classes accept user-supplied `java_options` 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: ```python # nltk/internals.py, lines 211-217 (HEAD) if options is None: java_options = _java_options # validated by config_java() else: if isinstance(options, str): options = options.split() java_options = list(options) # NO validation cmd = [_java_
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-m4rf-3fr8-xwx3 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-79675 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.