CVE-2026-63312 PUBLISHED

NLTK StreamBackedCorpusView Bypasses pathsec.ENFORCE Arbitrary File Read

Assigner: VulnCheck
Reserved: 16.07.2026 Published: 22.08.2026 Updated: 22.08.2026

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 Vector: CVSS: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 Score: 8.7

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

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

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	High
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	nltk
Product	nltk
Versions	Default: unaffected affected from 0 to 3.10.0 (excl.) Version 3.10.0 is unaffected

Credits

meme-dm reporter

References

Problem Types

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') CWE