# CVE-2026-100647: vLLM before 0.29.0 CPU Exhaustion via unbounded cache_salt

> Unauthenticated attackers can cause denial of service in vLLM by sending oversized cache_salt values that stall the scheduler thread.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Sep 2026
- **Updated:** 28 Sep 2026
- **Also known as:** GHSA-hm89-h84f-px3x, GHSA-wpww-v874-ph2p, MINI-gg6v-m2h5-gppw, MINI-mq73-w596-rgm5, MINI-v2j4-95cc-vq33

## What is CVE-2026-100647?

CVE-2026-100647 is a medium-severity denial of service vulnerability in Vllm Vllm, published on 26 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

vLLM versions before 0.29.0 contain a denial-of-service vulnerability in the cache_salt parameter accepted on OpenAI-compatible and Anthropic API endpoints, which lacks maximum length validation and is processed on the single EngineCore scheduler thread. Unauthenticated attackers can send HTTP requests with multi-hundred-megabyte salt values that trigger expensive pickle serialization and SHA-256 hashing, stalling the scheduler thread and denying service to all concurrent requests.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-100647?

It affects 1 product.


Products: Vllm Vllm.

## How do I fix CVE-2026-100647?

Upgrade to a fixed version.

## Is CVE-2026-100647 being exploited?

There is no known exploitation of CVE-2026-100647 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-2026-100647 and fix it if it is affected.

What it is: CVE-2026-100647 is a medium-severity denial of service vulnerability in Vllm Vllm, published on 26 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-100647 in the wild and no public exploit code.

Affected product: Vllm Vllm. 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-2026-100647/ (Markdown: https://insights.sbomify.com/CVE-2026-100647/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-100647
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-100647
- OSV: https://osv.dev/vulnerability/CVE-2026-100647

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-100647/
Summaries are generated and may contain mistakes; the official description above is the record.