CVE-2026-81727

Summary

NLTK versions before 3.10.3 contain a filesystem containment bypass vulnerability in the Downloader.download and Downloader.incr_download methods that allows attackers to overwrite files outside the install root through pre-existing hardlinks. Attackers with write access to a shared downloader directory can create hardlinks pointing to outside-root files that are then overwritten during normal package extraction, mutating files outside the intended install tree.

Affected Software

Weaknesses

• CWE-59: Improper Link Resolution Before File Access ('Link Following')

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: poc
  • Automatable: no
  • Technical Impact: partial

Additional References

• https://github.com/nltk/nltk/security/advisories/GHSA-f794-5jv7-7672

References

• https://github.com/nltk/nltk/security/advisories/GHSA-f794-5jv7-7672
• https://www.vulncheck.com/advisories/nltk-before-3.10.3-hardlink-file-overwrite-via-downloader

• ←Previous
• Next→