CVE-2026-71513
NLTK 3.10.0 through 3.10.2 Remote Code Execution via AllowlistUnpickler Dotted-Name Bypass
CVSS Score
8.8
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-502 |
| Vendor | nltk |
| Product | nltk |
| Published | Aug 22, 2026 |
Stay Ahead of the Next One
Get instant alerts for nltk nltk
Be the first to know when new high vulnerabilities affecting nltk nltk are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
nltk / nltk
3.10.0 < 3.10.3
References
github.com: https://github.com/nltk/nltk/commit/c3e37113742a1ebeeb4f2ca58941f320f98805ea github.com: https://github.com/nltk/nltk github.com: https://github.com/nltk/nltk/blob/v3.10.2/nltk/picklesec.py#L119-L124 vulncheck.com: https://www.vulncheck.com/advisories/nltk-through-remote-code-execution-via-allowlistunpickler-dotted-name-bypass
Credits
Tohirov Fazliddin Mahmud o'g'li