# CVE-2026-68552: Coturn: uint16_t truncation overflow in STUN message length causes TCP stream framing bypass

> An unauthenticated remote attacker can cause a denial of service by sending crafted STUN messages that trigger an integer overflow, desynchronizing the TCP stream parser.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Aug 2026
- **Updated:** 21 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-68552, GHSA-m562-mf7x-q7rr, UBUNTU-CVE-2026-68552

## What is CVE-2026-68552?

CVE-2026-68552 is a medium-severity vulnerability in coturn, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.15.0, an unauthenticated remote client can send a STUN message over TCP or TLS with a body-length field from 65520 through 65532, causing the uint16_t len variable in stun_get_message_len_str() in src/client/ns_turn_msg.c to wrap when STUN_HEADER_LENGTH is added. The framing layer then consumes only 4 through 16 bytes, treats the remaining bytes as another message, desynchronizes the stream parser, and drops the attacking client's connection. Other clients and the server process are not affected. This issue is fixed in version 4.15.0.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-68552?


## How do I fix CVE-2026-68552?

Upgrade to a fixed version.

## Is CVE-2026-68552 being exploited?

There is no known exploitation of CVE-2026-68552 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68552 and fix it if it is affected.

What it is: CVE-2026-68552 is a medium-severity vulnerability in coturn, published on 19 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-68552 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-2026-68552/ (Markdown: https://insights.sbomify.com/CVE-2026-68552/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68552
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68552
- OSV: https://osv.dev/vulnerability/CVE-2026-68552

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68552/
Summaries are generated and may contain mistakes; the official description above is the record.