Vulnerability Details : CVE-2020-26257

Matrix is an ecosystem for open federated Instant Messaging and VoIP. Synapse is a reference "homeserver" implementation of Matrix. A malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a different room id in the path of a `/send_join`, `/send_leave`, `/invite` or `/exchange_third_party_invite` request. This can lead to a denial of service in which future events will not be correctly sent to other servers over federation. This affects any server which accepts federation requests from untrusted servers. The Matrix Synapse reference implementation before version 1.23.1 the implementation is vulnerable to this injection attack. Issue is fixed in version 1.23.1. As a workaround homeserver administrators could limit access to the federation API to trusted servers (for example via `federation_domain_whitelist`).
Published 2020-12-09 19:15:12
Updated 2022-10-12 14:01:42
Source GitHub, Inc.
View at NVD,   CVE.org
Vulnerability category: Cross site scripting (XSS)Denial of service

Exploit prediction scoring system (EPSS) score for CVE-2020-26257

EPSS FAQ
0.16%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 52 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2020-26257

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
4.0
 MEDIUM AV:N/AC:L/Au:S/C:N/I:N/A:P
8.0
2.9
 NIST
6.5
 MEDIUM CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
2.8
3.6
 NIST
6.5
 MEDIUM CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
2.8
3.6
 GitHub, Inc.

CWE ids for CVE-2020-26257

  • The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
    Assigned by: security-advisories@github.com (Secondary)
  • The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.
    Assigned by:
    • nvd@nist.gov (Primary)
    • security-advisories@github.com (Secondary)

References for CVE-2020-26257

Products affected by CVE-2020-26257

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