CVE-2026-80206 Affecting nltk package, versions <3.10.3-1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIANUNSTABLE-NLTK-19271318
- published27 Aug 2026
- disclosed26 Aug 2026
Introduced: 26 Aug 2026
NewCVE-2026-80206 (opens in a new tab)How to fix?
Upgrade Debian:unstable nltk to version 3.10.3-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream nltk package and not the nltk package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
NLTK before 3.10.3 contains a regular expression denial of service (ReDoS) vulnerability in the tgrep module. The _tgrep_node_action function compiles user-supplied regular expressions embedded in /regex/ pattern nodes and executes them via re.search against tree node labels without any validation or timeout. An attacker who controls the tgrep pattern (e.g., via tgrep_positions() or tgrep_compile() exposed to external input) can supply a pattern that triggers catastrophic backtracking, causing indefinite CPU saturation that blocks the Python process.