CVE-2026-21869
CVE-2026-21869 is a high-severity vulnerability in Ggml Llama.cpp with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.
Key facts
- Severity: High (CVSS 3.x base score 8.8)
- EPSS exploit prediction: 0% (35th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-1661
- Weakness: CWE-787
- Affected product: Ggml Llama.cpp
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-21869?
- 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.
- How severe is CVE-2026-21869?
- CVE-2026-21869 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2026-21869 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-21869?
- CVE-2026-21869 affects Ggml Llama.cpp. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-21869?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-21869 have an EU (EUVD) identifier?
- Yes. CVE-2026-21869 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1661.
- When was CVE-2026-21869 published?
- CVE-2026-21869 was published on 2026-01-08 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:ggml:llama.cpp:-:*:*:*:*:*:*:*
More vulnerabilities in Ggml Llama.cpp
- CVE-2024-42479 — Critical (CVSS 10.0): llama.cpp provides LLM inference in C/C++. The unsafe `data` pointer member in the `rpc_tensor` structure can cause…
- CVE-2026-34159 — Critical (CVSS 9.8): llama.cpp is an inference of several LLM models in C/C++. Prior to version b8492, the RPC backend's…
- CVE-2025-49847 — High (CVSS 8.8): llama.cpp is an inference of several LLM models in C/C++. Prior to version b5662, an attacker‐supplied GGUF model…
- CVE-2024-23605 — High (CVSS 8.8): A heap-based buffer overflow vulnerability exists in the GGUF library header.n_kv functionality of llama.cpp Commit…
- CVE-2024-23496 — High (CVSS 8.8): A heap-based buffer overflow vulnerability exists in the GGUF library gguf_fread_str functionality of llama.cpp Commit…
- CVE-2024-21836 — High (CVSS 8.8): A heap-based buffer overflow vulnerability exists in the GGUF library header.n_tensors functionality of llama.cpp…
All CVEs affecting Ggml Llama.cpp →
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