CVE-2021-21382

MITRE NVD CVE.ORG JSON API Print: PDF PDF

Summary

CVECVE-2021-21382
StatePUBLIC
Assigner[email protected]
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-06-11 21:15:00 UTC
Updated2022-10-21 22:44:00 UTC
DescriptionRestund is an open source NAT traversal server. The restund TURN server can be instructed to open a relay to the loopback address range. This allows you to reach any other service running on localhost which you might consider private. In the configuration that we ship (https://github.com/wireapp/ansible-restund/blob/master/templates/restund.conf.j2#L40-L43) the `status` interface of restund is enabled and is listening on `127.0.0.1`.The `status` interface allows users to issue administrative commands to `restund` like listing open relays or draining connections. It would be possible for an attacker to contact the status interface and issue administrative commands by setting `XOR-PEER-ADDRESS` to `127.0.0.1:{{restund_udp_status_port}}` when opening a TURN channel. We now explicitly disallow relaying to loopback addresses, 'any' addresses, link local addresses, and the broadcast address. As a workaround disable the `status` module in your restund configuration. However there might still be other services running on `127.0.0.0/8` that you do not want to have exposed. The `turn` module can be disabled. Restund will still perform STUN and this might already be enough for initiating calls in your environments. TURN is only used as a last resort when other NAT traversal options do not work. One should also make sure that the TURN server is set up with firewall rules so that it cannot relay to other addresses that you don't want the TURN server to relay to. For example other services in the same VPC where the TURN server is running. Ideally TURN servers should be deployed in an isolated fashion where they can only reach what they need to reach to perform their task of assisting NAT-traversal.

Risk And Classification

Problem Types: CWE-862

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Wire Restund All All All All

References

ReferenceSourceLinkTags
ansible-restund/restund.conf.j2 at master · wireapp/ansible-restund · GitHub MISC github.com
turn: block forwarding to loopback/any by z-dule · Pull Request #7 · wireapp/restund · GitHub MISC github.com
TALOS-2018-0732 || Cisco Talos Intelligence Group - Comprehensive Threat Intelligence MISC talosintelligence.com
Unsafe loopback forwarding interface · Advisory · wireapp/restund · GitHub CONFIRM github.com
Details about CVE-2020-26262, bypass of Coturn's default access control protection | Communication Breakdown - real-time communications security MISC www.rtcsec.com
Loopback bypass by using 0.0.0.0, [::1] or [::] as the peer address · Advisory · coturn/coturn · GitHub MISC github.com
Restund (TURN) servers — Wire documentation MISC docs.wire.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report