# CVE-2026-49340: gonic has arbitrary file write in createPlaylist: any authenticated user can write playlist M3U content to attacker-controlled path on the host

> Authenticated users can write arbitrary files to the host filesystem via path traversal in playlist creation, potentially leading to code execution.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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:** Yes
- **Published:** 19 Jun 2026
- **Updated:** 22 Jun 2026
- **Also known as:** GHSA-4gxv-p5g5-j7w7, GO-2026-5827

## What is CVE-2026-49340?

CVE-2026-49340 is a high-severity path traversal vulnerability in sentriz gonic, published on 19 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

gonic is a music streaming server / free-software subsonic server API implementation. Prior to version 0.21.0, a logic error in `ServeCreateOrUpdatePlaylist` allows any authenticated Subsonic user (including non-admin) to write playlist M3U content to an attacker-controlled absolute filesystem path on the gonic host, and to create intermediate directories with `0o777` permissions. The bug is independent of CVE-2026-49338 and CVE-2026-49339. It is an unreachable guard clause combined with no path containment in `Store.Write`. Version 0.21.0 patches the issue.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource), CWE-697 (Incorrect Comparison), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-49340?

3 open source packages ship an affected version, including go.senan.xyz/gonic.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `go.senan.xyz/gonic` | Go | All versions | 0.21.0 |
| `go.senan.xyz/gonic` | Go | All versions | 0.21.0 |
| `go.senan.xyz/gonic` | Go | All versions | 0.21.0 |

## How do I fix CVE-2026-49340?

Upgrade go.senan.xyz/gonic to 0.21.0 or later.

## Is CVE-2026-49340 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49340 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49340 and fix it if it is affected.

What it is: CVE-2026-49340 is a high-severity path traversal vulnerability in sentriz gonic, published on 19 Jun 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-2026-49340 exists.

Affected packages and fixed versions:
- go.senan.xyz/gonic (Go): affected all versions; fixed in 0.21.0
- go.senan.xyz/gonic (Go): affected all versions; fixed in 0.21.0
- go.senan.xyz/gonic (Go): affected all versions; fixed in 0.21.0

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-2026-49340/ (Markdown: https://insights.sbomify.com/CVE-2026-49340/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49340
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49340
- OSV: https://osv.dev/vulnerability/CVE-2026-49340

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49340/
Summaries are generated and may contain mistakes; the official description above is the record.