NLTK before 3.10.0 (affected versions <= 3.9.4) contains a server-side request forgery (SSRF) vulnerability in the validate_network_url() function in nltk/pathsec.py.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

1. Aug 22, 2026 · NIST NVD

   Detected

   NLTK before 3.10.0 (affected versions <= 3.9.4) contains a server-side request forgery (SSRF) vulnerability in the validate_network_url() function in nltk/pathsec.py. The _resolve_hostname() helper catches OSError and ValueError during socket.getaddrinfo() and returns an empty list; when DNS resolution fails, the validation loop executes no IP checks and the function fails open, allowing urlopen()

2. Oct 14, 2026 · NIST NVD

   Updated

   NLTK before 3.10.0 (affected versions <= 3.9.4) contains a server-side request forgery (SSRF) vulnerability in the validate_network_url() function in nltk/pathsec.py. The _resolve_hostname() helper catches OSError and ValueError during socket.getaddrinfo() and returns an empty list; when DNS resolution fails, the validation loop executes no IP checks and the function fails open, allowing urlopen()

Affected

• cpe nltk/nltkversion unspecified

Sources

• CVE.orgVulnerability recordCVE-2026-63311

  Official CVE identifier

  cve.org
• FIRST EPSSExploitation probabilityCVE-2026-63311

  30-day exploitation probability 0.3%

  first.org
• NIST NVDVulnerability recordCVE-2026-63311

  NLTK before 3.10.0 (affected versions <= 3.9.4) contains a server-side request forgery (SSRF) vulnerability in the validate_network_url() function in nltk/pathsec.py. The _resolve_hostname() helper catches OSError and ValueError during socket.getaddrinfo() and returns an empty li

  nvd.nist.gov

References

• Exploit · github.com
• Third Party Advisory · vulncheck.com