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.
This issue is fixed by #9321 and #9393.
The groups feature can be disabled (by setting enable_group_creation
to False
) to mitigate this issue. Note that it is disabled by default.
Note that the groups feature is not part of the Matrix specification and the chosen maximum lengths are arbitrary. Not all clients might abide by them.
github.com/matrix-org/synapse
github.com/matrix-org/synapse/pull/9321
github.com/matrix-org/synapse/pull/9393
github.com/matrix-org/synapse/security/advisories/GHSA-jrh7-mhhx-6h88
lists.fedoraproject.org/archives/list/[email protected]/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY
nvd.nist.gov/vuln/detail/CVE-2021-21393
pypi.org/project/matrix-synapse