CVE-2021-29471 | Date: (C)2021-05-11 (M)2023-12-22 |
Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.33.2 "Push rules" can specify conditions under which they will match, including `event_match`, which matches event content against a pattern including wildcards. Certain patterns can cause very poor performance in the matching engine, leading to a denial-of-service when processing moderate length events. The issue is patched in version 1.33.2. A potential workaround might be to prevent users from making custom push rules, by blocking such requests at a reverse-proxy.
CVSS Score and Metrics +CVSS Score and Metrics -CVSS V3 Severity: | CVSS V2 Severity: |
CVSS Score : 5.3 | CVSS Score : 5.0 |
Exploit Score: 3.9 | Exploit Score: 10.0 |
Impact Score: 1.4 | Impact Score: 2.9 |
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CVSS V3 Metrics: | CVSS V2 Metrics: |
Attack Vector: NETWORK | Access Vector: NETWORK |
Attack Complexity: LOW | Access Complexity: LOW |
Privileges Required: NONE | Authentication: NONE |
User Interaction: NONE | Confidentiality: NONE |
Scope: UNCHANGED | Integrity: NONE |
Confidentiality: NONE | Availability: PARTIAL |
Integrity: NONE | |
Availability: LOW | |
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