CVE-2020-26262

NameCVE-2020-26262
DescriptionCoturn is free open source implementation of TURN and STUN Server. Coturn before version 4.5.2 by default does not allow peers to connect and relay packets to loopback addresses in the range of `127.x.x.x`. However, it was observed that when sending a `CONNECT` request with the `XOR-PEER-ADDRESS` value of `0.0.0.0`, a successful response was received and subsequently, `CONNECTIONBIND` also received a successful response. Coturn then is able to relay packets to the loopback interface. Additionally, when coturn is listening on IPv6, which is default, the loopback interface can also be reached by making use of either `[::1]` or `[::]` as the peer address. By using the address `0.0.0.0` as the peer address, a malicious user will be able to relay packets to the loopback interface, unless `--denied-peer-ip=0.0.0.0` (or similar) has been specified. Since the default configuration implies that loopback peers are not allowed, coturn administrators may choose to not set the `denied-peer-ip` setting. The issue patched in version 4.5.2. As a workaround the addresses in the address block `0.0.0.0/8`, `[::1]` and `[::]` should be denied by default unless `--allow-loopback-peers` has been specified.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
ReferencesDLA-2522-1, DSA-4829-1
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
coturn (PTS)stretch4.5.0.5-1+deb9u2vulnerable
stretch (security)4.5.0.5-1+deb9u3fixed
buster, buster (security)4.5.1.1-1.1+deb10u2fixed
bookworm, sid, bullseye4.5.2-3fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
coturnsourcestretch4.5.0.5-1+deb9u3DLA-2522-1
coturnsourcebuster4.5.1.1-1.1+deb10u2DSA-4829-1
coturnsource(unstable)4.5.2-1

Notes

https://github.com/coturn/coturn/security/advisories/GHSA-6g6j-r9rf-cm7p
https://github.com/coturn/coturn/commit/ff5e5478a3e1b426bad053828099403cfc5c1f5f
https://github.com/coturn/coturn/commit/af50d63a152cd9505d38f02bc552848748805e7b
https://github.com/coturn/coturn/commit/6c774b9fb8d9d76576ece10a6429172ed3800466
https://github.com/coturn/coturn/commit/560684c894498285f9e4271f3c924ebf01f36307
https://github.com/coturn/coturn/commit/649cbf966181846ecdd7847e4543dd287a78d295
https://github.com/coturn/coturn/commit/9c7deff4b8ed8c323c87b9ede75481bd6bc3154d
https://github.com/coturn/coturn/commit/dd0ffdb51a4cddaf1d6662079fa91f6f32bd26a8
https://github.com/coturn/coturn/commit/d84028b6dbc9eb7d3f8828ec37ae02a0963257b6

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