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From: Salvatore Bonaccorso <carnil@debian.org>
To: Debian Bug Tracking System <submit@bugs.debian.org>
Subject: coturn: CVE-2026-27624
Message-ID: <177228545089.633979.5273606564688946636.reportbug@eldamar.lan>
X-Mailer: reportbug 13.2.0
Date: Sat, 28 Feb 2026 14:30:50 +0100
Delivered-To: submit@bugs.debian.org

Source: coturn
Version: 4.6.1-1
Severity: important
Tags: security upstream
X-Debbugs-Cc: carnil@debian.org, Debian Security Team <team@security.debian.org>

Hi,

The following vulnerability was published for coturn.

CVE-2026-27624[0]:
| Coturn is a free open source implementation of TURN and STUN Server.
| Coturn is commonly configured to block loopback and internal ranges
| using "denied-peer-ip" and/or default loopback restrictions.
| CVE-2020-26262 addressed bypasses involving "0.0.0.0", "[::1]" and
| "[::]", but IPv4-mapped IPv6 is not covered. When sending a
| "CreatePermission" or "ChannelBind" request with the "XOR-PEER-
| ADDRESS" value of "::ffff:127.0.0.1", a successful response is
| received, even though "127.0.0.0/8" is blocked via "denied-peer-ip".
| The root cause is that, prior to the updated fix implemented in
| version 4.9.0, three functions in "src/client/ns_turn_ioaddr.c" do
| not check "IN6_IS_ADDR_V4MAPPED". "ioa_addr_is_loopback()" checks
| "127.x.x.x" (AF_INET) and "::1" (AF_INET6), but not
| "::ffff:127.0.0.1." "ioa_addr_is_zero()" checks "0.0.0.0" and "::",
| but not "::ffff:0.0.0.0." "addr_less_eq()" used by
| "ioa_addr_in_range()" for "denied-peer-ip" matching: when the range
| is AF_INET and the peer is AF_INET6, the comparison returns 0
| without extracting the embedded IPv4. Version 4.9.0 contains an
| updated fix to address the bypass of the fix for CVE-2020-26262.


If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2026-27624
    https://www.cve.org/CVERecord?id=CVE-2026-27624
[1] https://github.com/coturn/coturn/security/advisories/GHSA-j8mm-mpf8-gvjg
[2] https://github.com/coturn/coturn/commit/b80eb898ba26552600770162c26a8ae7f3661b0b

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore
]