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Fedora 43 Coturn Important XSS Security Alert FEDORA-2026-c42d951aad

fedora
Calendar Grey June 23, 2026
Dist Fedora Esm H88
Critical security update for coturn in Fedora 43 addressing XSS through crafted usernames in TURN allocation.
Coturn 4.13.1 What's in this release Security fixes What's Changed Null-terminate server_name in stun_is_challenge_response_str

Summary

The Coturn TURN Server is a VoIP media traffic NAT traversal server and gateway.

It can be used as a general-purpose network traffic TURN server/gateway, too.

This implementation also includes some extra features. Supported RFCs:

TURN specs:

- RFC 5766 - base TURN specs

- RFC 6062 - TCP relaying TURN extension

- RFC 6156 - IPv6 extension for TURN

- Experimental DTLS support as client protocol.

STUN specs:

- RFC 3489 - "classic" STUN

- RFC 5389 - base "new" STUN specs

- RFC 5769 - test vectors for STUN protocol testing

- RFC 5780 - NAT behavior discovery support

The implementation fully supports the following client-to-TURN-server protocols:

- UDP (per RFC 5766)

- TCP (per RFC 5766 and RFC 6062)

- TLS (per RFC 5766 and RFC 6062); TLS1.0/TLS1.1/TLS1.2

- DTLS (experimental non-standard feature)

Supported relay protocols:

- UDP (per RFC 5766)

- TCP (per RFC 6062)

Supported user databases (for user repository, with passwords or keys, if

authentication is required):

- SQLite

- MySQL

- PostgreSQL

- Redis

Redis can also be used for status and statistics storage and notification.

Supported TURN authentication mechanisms:

- long-term

- TURN REST API (a modification of the long-term mechanism, for time-limited

secret-based authentication, for WebRTC applications)

The load balancing can be implemented with the following tools (either one or a

combination of them):

- network load-balancer server

- DNS-based load balancing

- built-in ALTERNATE-SERVER mechanism.

Update Information:

Coturn 4.13.1 What's in this release Security fixes What's Changed Null-terminate server_name in stun_is_challenge_response_str Canonicalize all IPv4-in-IPv6 encodings before peer-IP checks Auto-deny coturn's own database backend endpoints as relay peers Deny link-local / ULA / site-local relay peers by default Coturn 4.13.0 What's in this release More performance improvements for --udp-recvmmsg and --multiplex-peer. If your system does not rely on TURN unique ports give multiplexing a try - it has capacity to dramatically increase performance. Security fixes What's Changed Wrap atomic everywhere Fix sendmmsg stride bug in multiplex-peer UDP batch flush Reap TURN permissions/channels via a per-thread sweep instead of per-object timers Add --udp-sendmmsg-log to observe egress sendmmsg/UDP-GSO batching Expose recvmmsg/sendmmsg UDP batch sizes as Prometheus metrics Restrict recvmmsg fast path to shared fan-in sockets (make --udp-recvmmsg useful standalone) Enable...

Change Log

* Tue Jun 16 2026 Robert Scheck - 4.13.1-1 - Upgrade to 4.13.1 (#2488712 #c1) * Sun Jun 14 2026 Robert Scheck - 4.13.0-1 - Upgrade to 4.13.0 (#2488712) * Fri Jun 12 2026 Yaakov Selkowitz - 4.12.0-3 - Rebuilt for openssl 4.0

References


[ 1 ] Bug #2490558 - CVE-2026-43915 coturn: Coturn: Cross-Site Scripting (XSS) via crafted username in TURN allocation https://bugzilla.redhat.com/show_bug.cgi?id=2490558

Update Instructions

This update can be installed with the "dnf" update program. Use su -c 'dnf upgrade --advisory FEDORA-2026-c42d951aad' at the command line. For more information, refer to the dnf documentation available at http://dnf.readthedocs.io/en/latest/command_ref.html#upgrade-command-label

Severity
important
Lowest
Low
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Critical

Name: coturn
Product: Fedora 43
Version: 4.13.1
Release: 1.fc43
Summary: TURN/STUN & ICE Server

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