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GHSA-8q93-326v-3m7g

MediumCVSS 5.5 / 10
Published May 14, 2026·Last modified Jun 9, 2026
Affected Components(0)

No affected components available

Description

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.

Risk Scores
Base Score
5.5

The vulnerability requires local access to the device to be exploited. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.

Threat Intelligence
5.1

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.13%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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