CVE-2020-26262 Information

Description

Coturn 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.

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Reference

https://github.com/coturn/coturn/commit/abfe1fd08d78baa0947d17dac0f7411c3d948e4d https://github.com/coturn/coturn/blob/57180ab60afcaeb13537e69ae8cb8aefd8f3f546/ChangeLog#L48 https://github.com/coturn/coturn/security/advisories/GHSA-6g6j-r9rf-cm7p https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/G54UIUFTEC6RLPOISMB6FUW7456SBZC4/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/M4CJOPAQT43MYAFU3UROGLEXN3Z6RS4H/

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

CHANGED

Integrity Impact

LOW

Availability Impact

LOW

Base Score

NONE

Base Severity

7.2