CVE-2026-12876
Published:September 02, 2026
Updated:September 03, 2026
"nltk.parse.RecursiveDescentParser" (and "SteppingRecursiveDescentParser") enumerate parses top-down with no bound on the number of recursive steps. A small, crafted context-free grammar makes a short input consume unbounded CPU (and/or exhaust the Python recursion stack), pinning a process indefinitely — a denial of service.
Affected Packages
nltk (CONDA):
Affected version(s) >=2.0.3 <3.10.3Fix Suggestion:
Update to version 3.10.3https://github.com/nltk/nltk.git (GITHUB):
Affected version(s) >=v3.10.0 <v3.10.3Fix Suggestion:
Update to version v3.10.3nltk (PYTHON):
Affected version(s) >=0.8 <3.10.3Fix Suggestion:
Update to version 3.10.3Related Resources (5)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.9
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW