CVE-2026-71513

NLTK before 3.10.3 contains a remote code execution vulnerability in AllowlistUnpickler that validates only the pickle module string and not the global name, allowing attackers to resolve dotted names by attribute traversal to callables outside the allowlisted namespace. Attackers can craft untrusted transition-parser models that execute arbitrary commands when TransitionParser.parse loads the model through allowlisted_pickle_load.

CVSS v3 8.8 HIGH

8.8^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/nltk/nltk	Product
https://github.com/nltk/nltk/blob/v3.10.2/nltk/picklesec.py#L119-L124	Product
https://github.com/nltk/nltk/commit/c3e37113742a1ebeeb4f2ca58941f320f98805ea	Patch
https://www.vulncheck.com/advisories/nltk-through-remote-code-execution-via-allowlistunpickler-dotted-name-bypass	Third Party Advisory Patch

Configurations

Configuration 1 (hide)

cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*

History

16 Sep 2026, 13:19

Type	Values Removed	Values Added
First Time		Nltk nltk Nltk
CPE		cpe:2.3:a:nltk:nltk::::::::
References	~~() https://github.com/nltk/nltk -~~	() https://github.com/nltk/nltk - Product
References	~~() https://github.com/nltk/nltk/blob/v3.10.2/nltk/picklesec.py#L119-L124 -~~	() https://github.com/nltk/nltk/blob/v3.10.2/nltk/picklesec.py#L119-L124 - Product
References	~~() https://github.com/nltk/nltk/commit/c3e37113742a1ebeeb4f2ca58941f320f98805ea -~~	() https://github.com/nltk/nltk/commit/c3e37113742a1ebeeb4f2ca58941f320f98805ea - Patch
References	~~() https://www.vulncheck.com/advisories/nltk-through-remote-code-execution-via-allowlistunpickler-dotted-name-bypass -~~	() https://www.vulncheck.com/advisories/nltk-through-remote-code-execution-via-allowlistunpickler-dotted-name-bypass - Third Party Advisory, Patch

Information

Published : 2026-08-22 14:16

Updated : 2026-09-16 13:19

NVD link : CVE-2026-71513

Mitre link : CVE-2026-71513

CVE.ORG link : CVE-2026-71513

JSON object : View

Products Affected

nltk

nltk

CWE

CWE-502

Deserialization of Untrusted Data

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