#VU55395 Open redirect in Zimbra Collaboration - CVE-2021-35209

Vulnerability identifier: #VU55395

Vulnerability risk: Medium

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-35209

CWE-ID: CWE-601

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Zimbra Collaboration
Web applications / Webmail solutions

Vendor: Synacor Inc.

Description

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

The vulnerability exists due to improper sanitization of user-supplied data in ProxyServlet.java in the /proxy servlet. 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

Zimbra Collaboration: 8.8.0 - 9.0.0

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External links
https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23
https://wiki.zimbra.com/wiki/Security_Center
https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16

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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.