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VULNERABILITIES

CVE-2020-26890 Details

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.

Metrics

CVSS 3.x Severity and Vector Strings:

NIST: [email protected]CVSS-B:7.5 HIGHVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

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URLSource(s)Tag(s)
https://github.com/matrix-org/synapse/security/advisories/GHSA-4mp3-385r-v63f CVEPatchThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/G7YXMMYQP46PYL664JQUXCA3LPBJU7DQ/ CVE
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U34DPP4ZLOEDUY2ZCWOHQPU5GA5LYNUQ/ CVE
https://github.com/matrix-org/synapse/security/advisories/GHSA-4mp3-385r-v63f [email protected]PatchThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/G7YXMMYQP46PYL664JQUXCA3LPBJU7DQ/ [email protected]

see all 6 references

Weakness Enumeration

CWE-IDCWE NameSource
CWE-20Improper Input Validation[email protected]

Affected Products

ProductVersions
matrix synapse
< 1.20.0

CPE

  • cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*

Remediation

  • No remediation found in references.
fedoraproject fedora
32
33

CPE

  • cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
  • cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

Remediation

  • No remediation found in references.

Change History

8 change records found show changes

QUICK INFO

CVE Dictionary Entry:
CVE-2020-26890
NVD Published Date:
Nov 24, 2020
NVD Last Modified:
Jun 17, 2026
Source:
[email protected]
CVE-2020-26890 Details - Not Deferred