# CVE-2026-115916: vLLM: Out-of-vocabulary prompt token id passes input validation and triggers a CUDA device-side assert (engine crash / DoS)


- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 26 Oct 2026
- **Updated:** 26 Oct 2026
- **Also known as:** GHSA-q97c-p368-75c4, PYSEC-2026-4347

## What is CVE-2026-115916?

CVE-2026-115916 is a medium-severity vulnerability in Vllm Vllm, published on 26 Oct 2026. 

### Official description

vLLM is an inference and serving engine for large language models. Prior to 0.32.0, vllm/tokenizers/hf.py computes max_token_id with an off-by-one upper bound, allowing a pre-tokenized prompt ID equal to the vocabulary size to pass validation. For a tensor-parallel size of one and an exact multiple-of-64 vocabulary, VocabParallelEmbedding.forward does not mask that value before F.embedding uses it, causing a CUDA device-side assertion and terminating the engine. This issue is fixed in version 0.32.0.

Weakness: CWE-193 (Off-by-one Error), CWE-129 (Improper Validation of Array Index)

## Which versions are affected by CVE-2026-115916?

3 open source packages ship an affected version, including vllm. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `vllm` | PyPI | All versions | 0.32.0 |
| `vllm` | PyPI | All versions | 0.32.0 |
| `vllm` | PyPI | All versions | 0.32.0 |

Products: Vllm Vllm.

## How do I fix CVE-2026-115916?

Upgrade vllm to 0.32.0 or later.

## Is CVE-2026-115916 being exploited?

There is no known exploitation of CVE-2026-115916 in the wild and no public exploit code.

## Other vulnerabilities in Vllm Vllm

- [CVE-2025-32444](https://insights.sbomify.com/CVE-2025-32444/): vLLM Vulnerable to Remote Code Execution via Mooncake Integration (critical 10.0)
- [CVE-2026-22778](https://insights.sbomify.com/CVE-2026-22778/): vLLM leaks a heap address when PIL throws an error (critical 9.8)
- [CVE-2025-47277](https://insights.sbomify.com/CVE-2025-47277/): vLLM Allows Remote Code Execution via PyNcclPipe Communication Service (critical 9.8)
- [CVE-2024-11041](https://insights.sbomify.com/CVE-2024-11041/): Remote Code Execution in vllm-project/vllm (critical 9.8)
- [CVE-2026-48746](https://insights.sbomify.com/CVE-2026-48746/): vLLM: OpenAI auth bypass (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-115916 and fix it if it is affected.

What it is: CVE-2026-115916 is a medium-severity vulnerability in Vllm Vllm, published on 26 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-115916 in the wild and no public exploit code.

Affected packages and fixed versions:
- vllm (PyPI): affected all versions; fixed in 0.32.0
- vllm (PyPI): affected all versions; fixed in 0.32.0
- vllm (PyPI): affected all versions; fixed in 0.32.0

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-2026-115916/ (Markdown: https://insights.sbomify.com/CVE-2026-115916/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-115916
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-115916
- OSV: https://osv.dev/vulnerability/CVE-2026-115916

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-115916/
Summaries are generated and may contain mistakes; the official description above is the record.