Description
Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.16.0, dtls_server_input_handler() and create_new_connected_udp_socket() in src/apps/relay/dtls_listener.c retain OpenSSL dtls1_reassemble_fragment() state for a 35-byte fragmented ClientHello declaring a 650,000-byte handshake before cookie validation, allowing an unauthenticated remote sender using fresh UDP tuples to exhaust memory without TURN credentials, a completed handshake, a valid cookie, or source spoofing. This issue is fixed in version 4.16.0.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| coturn | coturn | < 4.16.0 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | coturn | 4.18.0-1 | — |
| Debian 13 | coturn | No fix yet | — |
| Debian 12 | coturn | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | coturn | No fix yet | — |
| Ubuntu 26.04 LTS | coturn | No fix yet | — |
| Ubuntu 24.04 LTS | coturn | No fix yet | — |
| Ubuntu 22.04 LTS | coturn | No fix yet | — |
| Ubuntu 20.04 LTS | coturn | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | coturn | No fix yet | — |
| Ubuntu 16.04 LTS | coturn | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | coturn | 4.17.2-1.1 | openSUSE-SU-2026:11617-1 |
Advisories 1
- openSUSE-SU-2026:11617-1 coturn-4.17.2-1.1 on GA media SUSE / openSUSE Security Updates · Aug 28, 2026
References
- https://github.com/coturn/coturn/security/advisories/GHSA-5x2p-4vqj-f6m4
- https://github.com/coturn/coturn/pull/2003
- https://github.com/coturn/coturn/pull/2012
- https://github.com/coturn/coturn/commit/37e13d1d60af8f1422c01b5e9f1c6bc355d03b85
- https://github.com/coturn/coturn/commit/beb4de9dcb6a475129595b943c9a34264420df09
- https://github.com/coturn/coturn/releases/tag/4.16.0