CVE-2025-71439: llama.cpp heap out-of-bounds read in tokenizer loading

CVE-2025-71439 · Severity: medium · CVSS 5.5 · Published 2026-10-27

llama.cpp is a C++ implementation of the Llama language model that powers AI inference applications. A crafted GGUF model file with oversized token IDs can trigger an out-of-bounds memory read when loading the tokenizer, crashing the llama-cli or llama-server applications that process the model.

Technologies: Ggml-Org Llama.Cpp. Vendors: Ggml-Org.

Quick answers

Is CVE-2025-71439 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2025-71439 being exploited in the wild.
How severe is CVE-2025-71439?
Medium severity, with a CVSS score of 5.5, published 27 October 2026.
Which products and versions are affected?
Ggml-Org Llama.Cpp before b5649.
Is there a fix for CVE-2025-71439?
Yes: fixed in b5649. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2025-71439 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2025-71439?
Check whether you run Ggml-Org Llama.Cpp at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Fixed in: b5649

Technical details

A heap out-of-bounds read vulnerability exists in the llama_vocab::impl::print_info() function when processing GGUF model files. An attacker can supply a crafted model with a short tokenizer.ggml.tokens array but large special token IDs, causing the code to read past the id_to_token buffer boundary. This results in a crash (denial of service) during model loading in llama-cli or llama-server.

Affected products

  • ggml-org llama.cpp before b5649

Timeline

  • 2026-10-27: disclosed

References

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