{"cve":"CVE-2020-26262","nvd":{"published":"2021-01-13T19:15:16.027","modified":"2026-06-17T03:07:56.967","status":"Modified","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N","score":7.2},"cwes":["CWE-441","CWE-682"],"references":["https://github.com/coturn/coturn/blob/57180ab60afcaeb13537e69ae8cb8aefd8f3f546/ChangeLog#L48","https://github.com/coturn/coturn/commit/abfe1fd08d78baa0947d17dac0f7411c3d948e4d","https://github.com/coturn/coturn/security/advisories/GHSA-6g6j-r9rf-cm7p","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/G54UIUFTEC6RLPOISMB6FUW7456SBZC4/","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M4CJOPAQT43MYAFU3UROGLEXN3Z6RS4H/"],"products":["coturn_project:coturn","fedoraproject:fedora"],"source":"nvd","synced_at":"2026-10-19T21:14:10.479542811+00:00"},"epss":{"cve":"CVE-2020-26262","score":0.01547,"percentile":0.75022,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}