A coturn security update has been released for Debian GNU/Linux 10 to address a flaw where a remote attacker can bypass the protection via a specially crafted request using a peer address of '0.0.0.0' and trick coturn in relaying to the loopback interface.

DSA 4829-1: coturn security update

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Debian Security Advisory DSA-4829-1 security@debian.org
  https://www.debian.org/security/ Salvatore Bonaccorso
January 11, 2021   https://www.debian.org/security/faq
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Package : coturn
CVE ID : CVE-2020-26262

A flaw was discovered in coturn, a TURN and STUN server for VoIP. By
default coturn does not allow peers on the loopback addresses
(127.x.x.x and ::1). A remote attacker can bypass the protection via a
specially crafted request using a peer address of '0.0.0.0' and trick
coturn in relaying to the loopback interface. If listening on IPv6 the
loopback interface can also be reached by using either [::1] or [::] as
the address.

For the stable distribution (buster), this problem has been fixed in
version 4.5.1.1-1.1+deb10u2.

We recommend that you upgrade your coturn packages.

For the detailed security status of coturn please refer to its security
tracker page at:
  https://security-tracker.debian.org/tracker/coturn

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://www.debian.org/security/