Vulnerability Name:

CVE-2021-21273 (CCN-197492)

Assigned:2020-12-22
Published:2021-02-25
Updated:2021-11-23
Summary: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 1.25.0, requests to user provided domains were not restricted to external IP addresses when calculating the key validity for third-party invite events and sending push notifications. This could cause Synapse to make requests to internal infrastructure. The type of request was not controlled by the user, although limited modification of request bodies was possible. For the most thorough protection server administrators should remove the deprecated `federation_ip_range_blacklist` from their settings after upgrading to Synapse v1.25.0 which will result in Synapse using the improved default IP address restrictions. See the new `ip_range_blacklist` and `ip_range_whitelist` settings if more specific control is necessary.
CVSS v3 Severity:6.1 Medium (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)
5.3 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): Required
Scope:Scope (S): Changed
Impact Metrics:Confidentiality (C): Low
Integrity (I): Low
Availibility (A): None
3.1 Low (CCN CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N)
2.7 Low (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N/E:U/RL:O/RC:C)
Exploitability Metrics:Attack Vector (AV): Network
Attack Complexity (AC): High
Privileges Required (PR): None
User Interaction (UI): Required
Scope:Scope (S): Unchanged
Impact Metrics:Confidentiality (C): None
Integrity (I): Low
Availibility (A): None
CVSS v2 Severity:5.8 Medium (CVSS v2 Vector: AV:N/AC:M/Au:N/C:P/I:P/A:N)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): Medium
Authentication (Au): None
Impact Metrics:Confidentiality (C): Partial
Integrity (I): Partial
Availibility (A): None
2.1 Low (CCN CVSS v2 Vector: AV:N/AC:H/Au:S/C:N/I:P/A:N)
Exploitability Metrics:Access Vector (AV): Network
Access Complexity (AC): High
Athentication (Au): Single_Instance
Impact Metrics:Confidentiality (C): None
Integrity (I): Partial
Availibility (A): None
Vulnerability Type:CWE-601
CWE-601
Vulnerability Consequences:Gain Access
References:Source: MITRE
Type: CNA
CVE-2021-21273

Source: XF
Type: UNKNOWN
matrix-cve202121273-open-redirect(197492)

Source: MISC
Type: Patch, Third Party Advisory
https://github.com/matrix-org/synapse/commit/30fba6210834a4ecd91badf0c8f3eb278b72e746

Source: MISC
Type: Patch, Third Party Advisory
https://github.com/matrix-org/synapse/pull/8821

Source: MISC
Type: Third Party Advisory
https://github.com/matrix-org/synapse/releases/tag/v1.25.0

Source: CCN
Type: Synapse GIT Repository
Open redirects on some federation and push requests

Source: CONFIRM
Type: Patch, Third Party Advisory
https://github.com/matrix-org/synapse/security/advisories/GHSA-v936-j8gp-9q3p

Source: FEDORA
Type: Mailing List, Third Party Advisory
FEDORA-2021-a627cfd31e

Source: CCN
Type: WhiteSource Vulnerability Database
CVE-2021-21273

Vulnerable Configuration:Configuration 1:
  • cpe:/a:matrix:synapse:*:*:*:*:*:*:*:* (Version < 1.25.0)

    • Configuration 2:
  • cpe:/o:fedoraproject:fedora:34:*:*:*:*:*:*:*

    • Configuration CCN 1:
  • cpe:/a:matrix:synapse:1.24.0:-:*:*:*:*:*:*

    • * Denotes that component is vulnerable
    BACK
    matrix synapse *
    fedoraproject fedora 34
    matrix synapse 1.24.0 -