CVE-2026-80205

8.7 HIGH 0.7% exploit odds Fix listed Denial of service

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of service disruption.
Exploit odds: 0.7% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-08-26 11:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-09-03 05:15 UTC Last updatedMost recent change to the record

Details

Published: 2026-08-26 11:16 UTC
Last modified: 2026-09-03 05:15 UTC
Exploit probability: 0.7% · EPSS, next 30 days
Weakness: CWE-1333
Record status: Modified

Affected

Nltk < 3.10.0

Attack profile CVSS 4.0 · 8.7

Attack vector: Network
Complexity: Low
Attack requirements: None
Privileges needed: None
User interaction: None
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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Fix and advisories

https://github.com/nltk/nltk/security/advisories/GHSA-rrv8-h7p8-rx55

References

NVD record · CVE.org record