CVE-2026-21869

CRITICAL CVSS 3.1: 9.8 EPSS 0.52%
Updated Feb 02, 2026
Ggml
Parameter Value
CVSS 9.8 (CRITICAL)
Type CWE-787 (Out-of-bounds Write)
Vendor Ggml
Public PoC No

llama.cpp is an inference of several LLM models in C/C++. In commits 55d4206c8 and prior, the n_discard parameter is parsed directly from JSON input in the llama.cpp server's completion endpoints without validation to ensure it's non-negative. When a negative value is supplied and the context fills up, llama_memory_seq_rm/add receives a reversed range and negative offset, causing out-of-bounds memory writes in the token evaluation loop.

This deterministic memory corruption can crash the process or enable remote code execution (RCE). There is no fix at the time of publication.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service

CVSS Vector v3.1

Weakness Type (CWE)

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Ggml Llama.Cpp
cpe:2.3:a:ggml:llama.cpp:-:*:*:*:*:*:*:*