Multiple vulnerabilities in Matrix Synapse

Published: 2021-03-01

Risk	Medium
Patch available	YES
Number of vulnerabilities	2
CVE-ID	CVE-2021-21273 CVE-2021-21274
CWE-ID	CWE-601 CWE-20
Exploitation vector	Network
Public exploit	N/A
Vulnerable software Subscribe	Synapse Server applications / Conferencing, Collaboration and VoIP solutions
Vendor

Security Bulletin

This security bulletin contains information about 2 vulnerabilities.

1) Open redirect

EUVDB-ID: #VU51006

Risk: Medium

CVSSv3.1: 4.1 [CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-21273

CWE-ID: CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

Exploit availability: No

Description

The vulnerability allows a remote attacker to redirect victims to arbitrary URL.

The vulnerability exists due to improper sanitization of user-supplied data. A remote attacker can create a link that leads to a trusted website, however, when clicked, redirects the victim to arbitrary domain.

Successful exploitation of this vulnerability may allow a remote attacker to perform a phishing attack and steal potentially sensitive information.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Synapse: before 1.25.0

External links

http://github.com/matrix-org/synapse/commit/30fba6210834a4ecd91badf0c8f3eb278b72e746
http://github.com/matrix-org/synapse/pull/8821
http://github.com/matrix-org/synapse/releases/tag/v1.25.0
http://github.com/matrix-org/synapse/security/advisories/GHSA-v936-j8gp-9q3p

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Input validation error

EUVDB-ID: #VU51007

Risk: Low

CVSSv3.1: 3.8 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-21274

CWE-ID: CWE-20 - Improper input validation