Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.33.2 "Push rules" can specify conditions under which they will match, including event_match, which matches event content against a pattern including wildcards. Certain patterns can cause very poor performance in the matching engine, leading to a denial-of-service when processing moderate length events. The issue is patched in version 1.33.2. A potential workaround might be to prevent users from making custom push rules, by blocking such requests at a reverse-proxy.
{
"unresolved_ranges": [
{
"vendor_product": "fedoraproject:fedora",
"extracted_events": [
{
"last_affected": "34"
}
],
"cpes": [
"cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*"
],
"source": "CPE_STRING"
}
]
}{
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "1.33.2"
}
],
"cpe": "cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*",
"source": [
"CPE_RANGE",
"REFERENCES"
]
}