# CVE-2026-35034: Jellyfin: Potential Application DoS from excessively large SyncPlay group names

> An authenticated user can cause a denial of service in Jellyfin by creating SyncPlay groups with excessively large names, leading to memory exhaustion.

- **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
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Apr 2026
- **Updated:** 15 Apr 2026
- **Also known as:** GHSA-v2jv-54xj-h76w

## What is CVE-2026-35034?

CVE-2026-35034 is a medium-severity denial of service vulnerability in jellyfin, published on 14 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Jellyfin is an open source self hosted media server. Versions prior to 10.11.7 contain a denial of service vulnerability in the SyncPlay group creation endpoint (POST /SyncPlay/New), where an authenticated user can create groups with names of unlimited size due to insufficient input validation. By sending large payloads combined with arbitrary group IDs, an attacker can lock out the endpoint for other clients attempting to join SyncPlay groups and significantly increase the memory usage of the Jellyfin process, potentially leading to an out-of-memory crash. This issue has been fixed in version 10.11.7.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-35034?

It affects 1 product.


Products: Jellyfin Jellyfin.

## How do I fix CVE-2026-35034?

No fix has been published for CVE-2026-35034 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-35034 being exploited?

There is no known exploitation of CVE-2026-35034 in the wild and no public exploit code.

## Other vulnerabilities in jellyfin

- [CVE-2026-35031](https://insights.sbomify.com/CVE-2026-35031/): Jellyfin: Potential RCE via subtitle upload path traversal + .strm chain (critical 10.0)
- [CVE-2026-31852](https://insights.sbomify.com/CVE-2026-31852/): Jellyfin Possible Organization/Secret Compromise from dangerous CI implementation (critical 10.0)
- [CVE-2026-35033](https://insights.sbomify.com/CVE-2026-35033/): Jellyfin: Potential SSRF + Arbitrary file read via stream argument injection (critical 9.3)
- [CVE-2023-30627](https://insights.sbomify.com/CVE-2023-30627/): jellyfin-web has a stored cross-site scripting vulnerability in devices.js (critical 9.1)
- [CVE-2023-30626](https://insights.sbomify.com/CVE-2023-30626/): Jellyfin vulnerable to directory traversal and file write causing arbitrary code execution (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-35034 and fix it if it is affected.

What it is: CVE-2026-35034 is a medium-severity denial of service vulnerability in jellyfin, published on 14 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-35034 in the wild and no public exploit code.

Affected product: jellyfin. 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-2026-35034/ (Markdown: https://insights.sbomify.com/CVE-2026-35034/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-35034
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-35034
- OSV: https://osv.dev/vulnerability/CVE-2026-35034

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-35034/
Summaries are generated and may contain mistakes; the official description above is the record.