# CVE-2026-90878: vllm-project vLLM Jinja Template Rendering completions resource consumption

> Remote attackers can cause resource exhaustion in vLLM via malicious Jinja templates in chat completions, requiring a patch to mitigate.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/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:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** GHSA-2h9j-24rv-h4c7

## What is CVE-2026-90878?

CVE-2026-90878 is a medium-severity denial of service vulnerability in vllm-project vLLM, published on 15 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A vulnerability was determined in vllm-project vLLM up to 0.27.1. This affects an unknown part of the file /v1/chat/completions of the component Jinja Template Rendering. This manipulation of the argument chat_template causes resource consumption. The attack can be initiated remotely. The exploit has been publicly disclosed and may be utilized. The pull request to fix this issue awaits acceptance.

Weakness: CWE-404 (Improper Resource Shutdown or Release), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-90878?


## How do I fix CVE-2026-90878?

No fix has been published for CVE-2026-90878 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-90878 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-90878 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90878 and fix it if it is affected.

What it is: CVE-2026-90878 is a medium-severity denial of service vulnerability in vllm-project vLLM, published on 15 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-90878 exists.

Affected product: vllm-project 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-2026-90878/ (Markdown: https://insights.sbomify.com/CVE-2026-90878/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90878
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90878
- OSV: https://osv.dev/vulnerability/CVE-2026-90878

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90878/
Summaries are generated and may contain mistakes; the official description above is the record.