Skip to main content
VulnerabilityPublished

CVE-2026-12261: nltk/nltk · Improper Access Control

Affects nltk/nltkSource CVE Database V5

0
Compare

Not known to be exploited · CVSS 5.3 Medium.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 3.0 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 7 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 5 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
nltknltk/nltkAffected
  • ≥ unspecified, ≤ latest
Fixed in–

AI-suggested

Until a fix is available, users should avoid installing untrusted or unverified packages via nltk.downloader and consider isolating environments to prevent cross-package contamination. Monitor official nltk channels for updates addressing this vulnerability.

Description

CVE-2026-12261 is a medium severity vulnerability in the nltk Python library's downloader component (nltk.downloader) affecting versions up to 3.9.4. The flaw allows cross-package resource and model poisoning because the downloader extracts package archives into shared namespaces without proper isolation and only validates package integrity after extraction. This enables one package to overwrite another's trusted resources, which remain active across interpreter restarts and can impact workflows relying on NLTK APIs.

References

Community reviews

Loading reviews…