CVE-2026-63312

NLTK before 3.10.0 contains an arbitrary local file read vulnerability in StreamBackedCorpusView that bypasses pathsec.ENFORCE by calling builtins.open() directly instead of pathsec.open(). Attackers who control the fileid argument can read arbitrary local files regardless of the ENFORCE setting, including sensitive system files and application credentials.

CVSS 4.0

8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

0.7% chance of exploitation in the next 30 days; higher than 50% of CVEs (scores of 2026-10-25)

CWE

CWE-22

Published

2026-08-22

Modified

2026-10-14

Record from

the NVD, synced 2026-10-19

Affected

• nltk:nltk

Packages (OSV)

References

• https://github.com/nltk/nltk/security/advisories/GHSA-x5ph-mj9p-rfr8
• https://www.vulncheck.com/advisories/nltk-streambackedcorpusview-bypasses-pathsec-enforce-arbitrary-file-read
• https://github.com/nltk/nltk/security/advisories/GHSA-x5ph-mj9p-rfr8

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