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

> Unauthenticated attackers can achieve remote code execution in llama.cpp RPC backend via memory corruption in tensor deserialization.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Apr 2026
- **Updated:** 2 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-34159, GHSA-j8rj-fmpv-wcxw, UBUNTU-CVE-2026-34159

## What is CVE-2026-34159?

CVE-2026-34159 is a critical memory corruption vulnerability in ggml-org llama.cpp, published on 1 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-34159?

It affects 1 product.


Products: Ggml Llama.cpp.

## How do I fix CVE-2026-34159?

Upgrade to a fixed version.

## Is CVE-2026-34159 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34159 exists.

Public exploit code:

- 0 Click RCE exploit for CVE-2026-34159 Lama.cpp RPC server (github_poc): https://github.com/casp3r0x0/CVE-2026-34159
- Critical buffer validation bypass in deserialize_tensor() (llama.cpp < b8492). Null tensor buffer skips bounds check, enabling unauthenticated arbitrary R/W via GRAPH_COMPUTE. ASLR bypass + RCE over TCP 50052. (github_poc): https://github.com/rohithronanki/CVE-2026-34159-Vulnerability-Research-Analysis-Detection
- CVE-2026-34159 PoC and exploit (github_poc): https://github.com/TeamN4C/SG-2026-0021

## Other vulnerabilities in ggml-org llama.cpp

- [CVE-2024-42479](https://insights.sbomify.com/CVE-2024-42479/): llama.cpp allows write-what-where in rpc_server::set_tensor (critical 10.0)
- [CVE-2026-43629](https://insights.sbomify.com/CVE-2026-43629/): llama.cpp b4882–b9058 Buffer Overflow in KV Cache State Restore (critical 9.2)
- [CVE-2026-43631](https://insights.sbomify.com/CVE-2026-43631/): llama.cpp b7492–b9060 Use-After-Free RCE via llama-server (critical 9.2)
- [CVE-2026-43632](https://insights.sbomify.com/CVE-2026-43632/): llama.cpp b7492–b9060 Use-After-Free in Tokenization Endpoints (critical 9.2)
- [CVE-2026-21869](https://insights.sbomify.com/CVE-2026-21869/): llama.cpp has Out-of-bounds Write in llama-server (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34159 and fix it if it is affected.

What it is: CVE-2026-34159 is a critical memory corruption vulnerability in ggml-org llama.cpp, published on 1 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34159 exists.

Affected product: ggml-org llama.cpp. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-34159/ (Markdown: https://insights.sbomify.com/CVE-2026-34159/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34159
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34159
- OSV: https://osv.dev/vulnerability/CVE-2026-34159

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34159/
Summaries are generated and may contain mistakes; the official description above is the record.