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CVE-2026-80205

NLTK before 3.10.0 ReDoS via Text.findall() unvalidated regex

High8.7EPSS 0.65%
Published
Updated
Reserved
Assigned by
VulnCheck

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.

Scores

CVSS scores of CVE-2026-80205, by who scored it
Scored byCVSSScoreVector
VulnCheckCNA (assigner)4.0High8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
VulnCheckCNA (assigner)3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVDNVD · Modified4.0High8.7CVSS: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
EPSS (exploitation in 30 days)
0.65% · top 49% of all CVEs (6 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: yes · Technical impact: partial
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The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.7.

Weakness

Affected products

  • nltk · nltk

    • affected < 3.10.0
    • unaffected 3.10.0

Affected packages

From reviewed advisories of the GitHub Advisory Database.

References (3)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .