CVE-2026-102533
Published:October 12, 2026
Updated:October 13, 2026
Impact Synapse accepts to-device messages from remote homeservers, even if the remote homeserver has spoofed the "sender" field such that it appears to have come from a different homeserver. Homeservers that do not federate or only participate in a closed, trusted federation are not affected. ### Patches Update to Synapse 1.157.2 or later. See the table below for patched versions of "Element Server Suite" (https://element.io/en/server-suite), including Long-Term Support (LTS) versions. | | 25.10 LTS | 26.4 LTS | Latest | |:--|--|--|--| | ESS Pro | "25.10.14+lts" | "26.4.9+lts" | "26.7.2" | | ESS Classic | "25.10.09-gui" | "26.04.04-gui" | ⸻ | | ESS Community | ⸻ | ⸻ | "26.7.2" | | ESS TI-Messenger | "25.10.10" | "26.4.5" | "26.7.0" | ### Workarounds None known. ### Identifiers - ELEMENTSEC-2024-1520 ### For more information If you have any questions or comments about this advisory, please email us at "security at element.io" (mailto:security@element.io).
Affected Packages
https://github.com/element-hq/synapse.git (GITHUB):
Affected version(s) >=v1.0.0rc1 <v1.157.2Fix Suggestion:
Update to version v1.157.2matrix-synapse (PYTHON):
Affected version(s) >=1.0.0rc1 <1.157.2Fix Suggestion:
Update to version 1.157.2Related Resources (3)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Authentication Bypass by Spoofing