high7.5
CVE-2026-80205
NLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall() and TokenSearcher.findall() methods that accept user…
Impact
NLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall() and TokenSearcher.findall() methods that accept user-supplied regular expressions without validation or timeout. Attackers can supply crafted regex patterns that cause catastrophic backtracking, resulting in indefinite CPU saturation and denial of service to all users of the Python process.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | nltk | <= 3.9.4 | 3.10.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Nltk | Nltk | before 3.10.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-rrv8-h7p8-rx55
- https://github.com/nltk/nltk/security/advisories/GHSA-rrv8-h7p8-rx55
- https://nvd.nist.gov/vuln/detail/CVE-2026-80205
- https://github.com/nltk/nltk/pull/3674
- https://github.com/nltk/nltk/commit/d8e47539317b571ab1422981f5b9653d5eae1249
- https://github.com/nltk/nltk/releases/tag/v3.10.0
- https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3750.yaml
- https://www.vulncheck.com/advisories/nltk-before-3.10.0-redos-via-text-findall-unvalidated-regex
- http://www.openwall.com/lists/oss-security/2026/09/01/3