# CVE-2026-43915: Coturn: Stored Cross-Site Scripting (XSS) in web-admin interface via TURN username

> An attacker can inject malicious scripts into the Coturn web-admin interface via TURN usernames, potentially compromising admin sessions.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 18 Jun 2026
- **Updated:** 18 Jun 2026
- **Also known as:** DEBIAN-CVE-2026-43915, GHSA-xxf5-9vj2-g84j, UBUNTU-CVE-2026-43915

## What is CVE-2026-43915?

CVE-2026-43915 is a medium-severity cross-site scripting vulnerability in coturn, published on 18 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Coturn is a free open source implementation of TURN and STUN Server. Versions prior to 4.11.0 contain a stored cross-site scripting (XSS) vulnerability in the web-admin HTTPS interface. An attacker who can create a TURN allocation with a crafted USERNAME value can inject HTML/JavaScript that executes when an authenticated web-admin user views the TURN session list. In configurations using anonymous TURN access (--no-auth), this may be exploitable without TURN credentials. In authenticated deployments, exploitation requires valid TURN credentials or control over a provisioned username. This issue has been fixed in version 4.11.0.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-43915?

It affects 1 product.


Products: Coturn Project Coturn.

## How do I fix CVE-2026-43915?

Upgrade to a fixed version.

## Is CVE-2026-43915 being exploited?

There is no known exploitation of CVE-2026-43915 in the wild and no public exploit code.

## Other vulnerabilities in coturn

- [CVE-2018-4056](https://insights.sbomify.com/CVE-2018-4056/): SQL injection in coTURN (critical 9.1)
- [CVE-2026-43994](https://insights.sbomify.com/CVE-2026-43994/): Coturn: Stack buffer overflow in decode_oauth_token_gcm() (high 8.1)
- [CVE-2018-4058](https://insights.sbomify.com/CVE-2018-4058/): Server-side request forgery in coTURN (high 7.7)
- [CVE-2026-40613](https://insights.sbomify.com/CVE-2026-40613/): Coturn: Misaligned Memory Access in coturn STUN Attribute Parser (Remote DoS on ARM64) (high 7.5)
- [CVE-2026-53450](https://insights.sbomify.com/CVE-2026-53450/): Coturn: IPv4-mapped 127.0.0.1 bypasses default loopback peer protection (high 7.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43915 and fix it if it is affected.

What it is: CVE-2026-43915 is a medium-severity cross-site scripting vulnerability in coturn, published on 18 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-43915 in the wild and no public exploit code.

Affected product: coturn. 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-2026-43915/ (Markdown: https://insights.sbomify.com/CVE-2026-43915/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43915
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43915
- OSV: https://osv.dev/vulnerability/CVE-2026-43915

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43915/
Summaries are generated and may contain mistakes; the official description above is the record.