CVE-2026-12252: Safety · NLTK Stanford wrapper classes execute untrusted JAR files without verification
Affects safetySource GCVE Database
Mentioned vulnerabilities
Not known to be exploited · CVSS 7.8 High : upgrade to 3.7.0_7 soon.
Data as of 30 Oct 2026, 07:30 UTC
- Patch
- Available – fixed in 3.7.0_7
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 4 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade safety to 3.7.0_7.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Homebrewsafetypkg:brew/safetyOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In nltk/nltk versions 3.9.3 and earlier, five Stanford interface classes (StanfordPOSTagger, StanfordNERTagger, StanfordParser, StanfordDependencyParser, and StanfordNeuralDependencyParser) are vulnerable to untrusted JAR code execution. These classes accept user-controllable JAR paths and execute them via the `java()` function, which invokes `subprocess.Popen()` without integrity verification. This vulnerability is identical to CVE-2026-0848, which was fixed for StanfordSegmenter by adding SHA256 verification. However, the fix was not applied to these additional classes, leaving them susceptible to arbitrary code execution when loading untrusted JAR files.
References
- nvd.nist.gov/vuln/detail/CVE-2026-12252 (opens in a new tab)
- github.com/nltk/nltk/pull/3743 (opens in a new tab)
- github.com/nltk/nltk/commit/006f4b83d430147b067b81e2cddd226d6fa405c8 (opens in a new tab)
- github.com/nltk/nltk/commit/24777f0cb8c33ed2839d16e0f8169a3c312a6806 (opens in a new tab)
- github.com/nltk/nltk (opens in a new tab)
- github.com/nltk/nltk/releases/tag/v3.10.3 (opens in a new tab)
- github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-2085.yaml (opens in a new tab)
- huntr.com/bounties/f5c93982-0cc9-4e2e-bb85-1b6ab29a2efb (opens in a new tab)