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CVE PROGRAM SOURCE RECORD6.9 Medium

CVE-2026-63311

NLTK before 3.10.0 SSRF via DNS Resolution Failure

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Status
Published
Published
Updated
Assigning organization
VulnCheck

Description

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() to proceed without validation. An attacker who can trigger DNS resolution failures or use DNS rebinding can bypass SSRF protections and reach restricted network resources, including cloud metadata endpoints (e.g., 169.254.169.254).

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

nltk nltk

Default version status: unaffected

  • 0 to < 3.10.0affected
  • 3.10.0unaffected
pkg:pypi/nltk

References