High severity7.5NVD Advisory· Published Nov 24, 2020· Updated Jun 17, 2026
CVE-2020-26890
CVE-2020-26890
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.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
matrix-synapsePyPI | < 1.20.0 | 1.20.0 |
Affected products
2- Matrix/Synapsedescription
Patches
Vulnerability mechanics
References
9- github.com/matrix-org/synapse/security/advisories/GHSA-4mp3-385r-v63fnvdPatchThird Party AdvisoryWEB
- github.com/advisories/GHSA-4mp3-385r-v63fghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2020-26890ghsaADVISORY
- github.com/pypa/advisory-database/tree/main/vulns/matrix-synapse/PYSEC-2020-237.yamlghsaWEB
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/G7YXMMYQP46PYL664JQUXCA3LPBJU7DQghsaWEB
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/U34DPP4ZLOEDUY2ZCWOHQPU5GA5LYNUQghsaWEB
- pypi.org/project/matrix-synapseghsaWEB
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/G7YXMMYQP46PYL664JQUXCA3LPBJU7DQ/nvd
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U34DPP4ZLOEDUY2ZCWOHQPU5GA5LYNUQ/nvd
News mentions
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