PatchTheCVECVE-2026-80205: NLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall() and
CVE-2026-80205 is a high-severity flaw (CVSS 7.5) affecting nltk. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- High severity
- Public exploit reference
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.5 (High) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.7% (top 49%) |
| CISA exploited list | No |
| Weakness | CWE-1333 |
| Published | 2026-08-26 |
| Last modified | 2026-09-03 |
Last updated 2026-09-03 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-80205?
nltk: upgrade to 3.10.0. Exact commands for each OS are on this page.
Is CVE-2026-80205 being exploited?
CVE-2026-80205 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-80205 affect?
CVE-2026-80205 affects nltk. Severity is high (CVSS 7.5). 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
How urgent is CVE-2026-80205?
Priority 49/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action
Software pages
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