# CVE-2026-2069: ggml-org llama.cpp GBNF Grammar llama-grammar.cpp llama_grammar_advance_stack stack-based overflow

> A local attacker can trigger a stack-based buffer overflow in the GBNF grammar handler of llama.cpp, potentially leading to code execution or denial of service.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Feb 2026
- **Updated:** 23 Feb 2026
- **Also known as:** DEBIAN-CVE-2026-2069, GHSA-f8m3-93xm-637c, UBUNTU-CVE-2026-2069

## What is CVE-2026-2069?

CVE-2026-2069 is a medium-severity memory corruption vulnerability in ggml-org llama.cpp, published on 6 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A flaw has been found in ggml-org llama.cpp up to 55abc39. Impacted is the function llama_grammar_advance_stack of the file llama.cpp/src/llama-grammar.cpp of the component GBNF Grammar Handler. This manipulation causes stack-based buffer overflow. The attack needs to be launched locally. The exploit has been published and may be used. Patch name: 18993. To fix this issue, it is recommended to deploy a patch.

Weakness: CWE-121 (Stack-based Buffer Overflow), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-2069?


## How do I fix CVE-2026-2069?

No fix has been published for CVE-2026-2069 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-2069 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-2069 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-2069 and fix it if it is affected.

What it is: CVE-2026-2069 is a medium-severity memory corruption vulnerability in ggml-org llama.cpp, published on 6 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-2069 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-2026-2069/ (Markdown: https://insights.sbomify.com/CVE-2026-2069/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-2069
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-2069
- OSV: https://osv.dev/vulnerability/CVE-2026-2069

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-2069/
Summaries are generated and may contain mistakes; the official description above is the record.