High severity7.5NVD Advisory· Published Aug 26, 2026· Updated Sep 3, 2026
CVE-2026-80205
CVE-2026-80205
Description
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
nltkPyPI | < 3.10.0 | 3.10.0 |
Affected products
1Patches
Vulnerability mechanics
References
9- github.com/nltk/nltk/security/advisories/GHSA-rrv8-h7p8-rx55nvdExploitVendor AdvisoryWEB
- github.com/advisories/GHSA-rrv8-h7p8-rx55ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-80205ghsaADVISORY
- www.vulncheck.com/advisories/nltk-before-3.10.0-redos-via-text-findall-unvalidated-regexnvdThird Party AdvisoryWEB
- www.openwall.com/lists/oss-security/2026/09/01/3nvdWEB
- github.com/nltk/nltk/commit/d8e47539317b571ab1422981f5b9653d5eae1249ghsaWEB
- github.com/nltk/nltk/pull/3674ghsaWEB
- github.com/nltk/nltk/releases/tag/v3.10.0ghsaWEB
- github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3750.yamlghsaWEB
News mentions
1- Nltk Library: 16 Vulnerabilities Including Critical RCE Disclosed in BatchVypr Intelligence · Aug 27, 2026