title: Improper validation of receipts allows forged read receipts in matrix synapse
description: Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Users were able to forge read receipts for any event (if they knew the room ID and event ID). Note that the users were not able to view the events, but simply mark it as read. This could be confusing as clients will show the event as read by the user, even if they are not in the room. This issue has been patched in version 1.93.0. Users are advised to upgrade. There are no known workarounds for this issue.
problem types: CWE-285: Improper Authorization
affected:
{
vendor: matrix-org
product: synapse
versions:
version: >= 0.34.0, < 1.93.0, status: affected
}
metrics:
cvssV3_1: [
attackComplexity: HIGH
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 3.1
baseSeverity: LOW
confidentialityImpact: NONE
integrityImpact: LOW
privilegesRequired: LOW
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
version: 3.1
]