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.
Published 2020-11-24 03:15:13
Updated 2021-07-21 11:39:24
Source MITRE
View at NVD,   CVE.org
Vulnerability category: Input validationDenial of service

Exploit prediction scoring system (EPSS) score for CVE-2020-26890

0.66%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 77 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2020-26890

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
5.0
MEDIUM AV:N/AC:L/Au:N/C:N/I:N/A:P
10.0
2.9
NIST
7.5
HIGH CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.9
3.6
NIST

CWE ids for CVE-2020-26890

  • The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
    Assigned by: nvd@nist.gov (Primary)

Products affected by CVE-2020-26890

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