- CVSS
- HIGH · 8.8 v3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Published
- 2026-01-08
- Weakness
- CWE-787
- Source
- nvd.nist.gov/vuln/detail/CVE-2026-21869
Description
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.
References
How GTK Cyber trains on this
AI security training at GTK Cyber covers the LLM and ML-pipeline vulnerability classes that vulnerabilities like CVE-2026-21869 fall into. Our hands-on courses are taught by Charles Givre and other practitioners who break and defend production AI systems.