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GHSA-jrh7-mhhx-6h88

Denial of service (via resource exhaustion) due to improper input validation on groups/communities endpoints

Source: GitHub Advisory Database (reviewed) Moderate CVE-2021-21393

Packages

EcosystemPackageAffectedFixed in
PyPI matrix-synapse < 1.28.0 1.28.0

Details

As written in the advisory (Markdown source, shown as plain text).

### Impact Missing input validation of some parameters on the groups (also known as communities) endpoints could cause excessive use of disk space and memory leading to resource exhaustion. Additionally clients may have issues rendering large fields. ### Patches This issue is fixed by #9321 and #9393. ### Workarounds The groups feature can be disabled (by setting `enable_group_creation` to `False`) to mitigate this issue. Note that it is disabled by default. ### Other information Note that the groups feature is not part of the [Matrix specification](https://matrix.org/docs/spec/) and the chosen maximum lengths are arbitrary. Not all clients might abide by them.

References

External links from the advisory. They lead to third-party sites.