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GHSA-rfq8-j7rh-8hf2
No affected components available
Impact
In Synapse before 1.120.1, multipart/form-data requests can in certain configurations transiently increase memory consumption beyond expected levels while processing the request, which can be used to amplify denial of service attacks.
Patches
Synapse 1.120.1 resolves the issue by denying requests with unsupported multipart/form-data content type.
Workarounds
Limiting request sizes or blocking the multipart/form-data content type before the requests reach Synapse, for example in a reverse proxy, alleviates the issue. Another approach that mitigates the attack is to use a low max_upload_size in Synapse.
References
- https://github.com/twisted/twisted/issues/4688#issuecomment-1167705518
- https://github.com/twisted/twisted/issues/4688#issuecomment-2385711609
For more information
If you have any questions or comments about this advisory, please email us at security at element.io.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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