SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2020-26890

Matrix Synapse before 1.20.0 erroneously permits non-standard NaN, Infinity, and -Infinity JSON values in fields of m.room.member events, allowing remote attackers to execute a denial of service attack against the federation and common Matrix clients.

HIGH 7.5EPSS 3.00%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (3.00%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

Matrix Synapse before 1.20.0 erroneously permits non-standard NaN, Infinity, and -Infinity JSON values in fields of m.room.member events, allowing remote attackers to execute a denial of service attack against the federation and common Matrix clients. If such a malformed event is accepted into the room's state, the impact is long-lasting and is not fixed by an upgrade to a newer version, requiring the event to be manually redacted instead. Since events are replicated to servers of other room members, the impact is not constrained to the server of the event sender.

CVSS 3.1
7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
3.00% probability · 87th percentile
CISA KEV
Not listed
Weakness
CWE-20
Affected
matrix/synapse · fedoraproject/fedora
Source
cve@mitre.org

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.