CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:N/I:N/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS
Percentile
51.9%
Severity: Medium
Date : 2021-05-25
CVE-ID : CVE-2021-29471
Package : matrix-synapse
Type : denial of service
Remote : Yes
Link : https://security.archlinux.org/AVG-1943
The package matrix-synapse before version 1.33.2-1 is vulnerable to
denial of service.
Upgrade to 1.33.2-1.
The problem has been fixed upstream 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.
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.
A remote attacker could cause high CPU usage on the server using
crafted push rules, leading to denial of service.
https://bugs.archlinux.org/task/70801
https://github.com/matrix-org/synapse/security/advisories/GHSA-x345-32rc-8h85
https://github.com/matrix-org/synapse/commit/03318a766cac9f8b053db2214d9c332a977d226c
https://security.archlinux.org/CVE-2021-29471
OS | Version | Architecture | Package | Version | Filename |
---|---|---|---|---|---|
ArchLinux | any | any | matrix-synapse | < 1.33.2-1 | UNKNOWN |
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:N/I:N/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS
Percentile
51.9%