CVE-2021-21273

Summary

CVECVE-2021-21273
StatePUBLIC
Assigner[email protected]
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-02-26 18:15:00 UTC
Updated2023-11-07 03:29:00 UTC
DescriptionSynapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.25.0, requests to user provided domains were not restricted to external IP addresses when calculating the key validity for third-party invite events and sending push notifications. This could cause Synapse to make requests to internal infrastructure. The type of request was not controlled by the user, although limited modification of request bodies was possible. For the most thorough protection server administrators should remove the deprecated `federation_ip_range_blacklist` from their settings after upgrading to Synapse v1.25.0 which will result in Synapse using the improved default IP address restrictions. See the new `ip_range_blacklist` and `ip_range_whitelist` settings if more specific control is necessary.

Risk And Classification

Problem Types: CWE-601

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Fedoraproject Fedora 34 All All All
Application Matrix Synapse All All All All
Application Matrix Synapse All All All All

References

ReferenceSourceLinkTags
Release v1.25.0 · matrix-org/synapse · GitHub MISC github.com Third Party Advisory
Apply an IP range blacklist to push and key revocation requests. (#8821) · matrix-org/synapse@30fba62 · GitHub MISC github.com Patch, Third Party Advisory
Apply the federation_ip_range_blacklist to push and key revocation requests by clokep · Pull Request #8821 · matrix-org/synapse · GitHub MISC github.com Patch, Third Party Advisory
[SECURITY] Fedora 34 Update: matrix-synapse-1.38.1-1.fc34 - package-announce - Fedora Mailing-Lists lists.fedoraproject.org
[SECURITY] Fedora 34 Update: matrix-synapse-1.38.1-1.fc34 - package-announce - Fedora Mailing-Lists FEDORA lists.fedoraproject.org
Open redirects on some federation and push requests · Advisory · matrix-org/synapse · GitHub CONFIRM github.com Patch, Third Party Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 281765 Fedora Security Update for matrix (FEDORA-2021-a627cfd31e)
  • 981374 Python (pip) Security Update for matrix-synapse (GHSA-v936-j8gp-9q3p)
© 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.

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