### Impact Local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. Homeservers that trust all their local users are not at risk. ### Patches Update to Synapse 1.152.1 or later. ### Workarounds If Synapse is deployed behind a reverse proxy, the reverse proxy could be configured to limit the rate of user requests, preventing or increasing the difficulty of the attack. ### Identifiers - ELEMENTSEC-2026-1706 ### For more information If you have any questions or comments about this advisory, please email us at [security at element.io](mailto:[email protected]).
Update matrix-synapse to 1.152.1 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanSynapse CPU starvation (Denial of Service) affects matrix-synapse (pip). Severity is high. ### Impact Local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. Homeservers that trust all their local users are not at risk. ### Patches Update to Synapse 1.152.1 or later. ### Workarounds If Synapse is deployed behind a reverse proxy, the reverse proxy could be configured to limit the rate of user requests, preventing or increasing the difficulty of the attack. ### Identifiers - ELEMENTSEC-2026-1706 ### For more information If you have any questions or comments about this advisory, please email us at [security at element.io](mailto:[email protected]).
AI coding agents often install or upgrade packages automatically in pip. A high vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| matrix-synapse |
### Impact Local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. Homeservers that trust all their local users are not at risk. ### Patches Update to Synapse 1.152.1 or later. ### Workarounds If Synapse is deployed behind a reverse proxy, the reverse proxy could be configured to limit the rate of user requests, preventing or increasing the difficulty of the attack. ### Identifiers - ELEMENTSEC-2026-1706 ### For more information If you have any questions or comments about this advisory, please email us at [security at element.io](mailto:[email protected]).
Update matrix-synapse to 1.152.1 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanSynapse CPU starvation (Denial of Service) affects matrix-synapse (pip). Severity is high. ### Impact Local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. Homeservers that trust all their local users are not at risk. ### Patches Update to Synapse 1.152.1 or later. ### Workarounds If Synapse is deployed behind a reverse proxy, the reverse proxy could be configured to limit the rate of user requests, preventing or increasing the difficulty of the attack. ### Identifiers - ELEMENTSEC-2026-1706 ### For more information If you have any questions or comments about this advisory, please email us at [security at element.io](mailto:[email protected]).
AI coding agents often install or upgrade packages automatically in pip. A high vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| matrix-synapse |
| <1.152.1 |
| 1.152.1 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard| <1.152.1 |
| 1.152.1 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard