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Case File

CVE-2021-32659

MEDIUM · CVSS 6.5 EPSS 0.94% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2021-06-16 · Last synced 2026-08-04

CyberRota Analysis

This is a medium severity vulnerability with a CVSS score of 6.5. Public exploit code or proof-of-concept references have been detected in its references.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2021-32659
Severity
MEDIUM
CVSS
6.5
EPSS
0.94%

Original NVD Description

Matrix-appservice-bridge is the bridging service for the Matrix communication program's application services. In versions 2.6.0 and earlier, if a bridge has room upgrade handling turned on in the configuration (the `roomUpgradeOpts` key when instantiating a new `Bridge` instance.), any `m.room.tombstone` event it encounters will be used to unbridge the current room and bridge into the target room. However, the target room `m.room.create` event is not checked to verify if the `predecessor` field contains the previous room. This means that any malicious admin of a bridged room can repoint the traffic to a different room without the new room being aware. Versions 2.6.1 and greater are patched. As a workaround, disabling the automatic room upgrade handling can be done by removing the `roomUpgradeOpts` key from the `Bridge` class options.

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