The on_get_missing_events function in handlers/federation.py in Matrix Synapse before 0.31.1 has a security bug in the get_missing_events federation API where event visibility rules were not applied correctly.
{
"extracted_events": [
{
"cpe": "cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "0.31.1"
}
],
"source": "CPE_RANGE"
},
{
"original_tag": "v0.31.1",
"range": [
{
"fixed": "aefcc0f5e5e3b4ce6020dd895045ddf5f83ba5d9"
}
],
"source": "REFERENCES_TAG"
}
]
}