CVE-2021-34807

Name: CVE-2021-34807
Creator: NVD / NIST
Published: 2021-07-02T19:15:08.33+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 0.97%

Last modified Jun 17, 2026

CVE-2021-34807 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. An open redirect vulnerability exists in the /preauth Servlet in Zimbra Collaboration Suite through 9.0. To exploit the vulnerability, an attacker would need to have obtained a valid zimbra auth token or a valid preauth token. EPSS estimates a 0.97% chance of exploitation in the next 30 days.

Description

An open redirect vulnerability exists in the /preauth Servlet in Zimbra Collaboration Suite through 9.0. To exploit the vulnerability, an attacker would need to have obtained a valid zimbra auth token or a valid preauth token. Once the token is obtained, an attacker could redirect a user to any URL via isredirect=1&redirectURL= in conjunction with the token data (e.g., a valid authtoken= value).

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.97%

57.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-601

Affected Software

Vendor	Product	Versions
Zimbra	Collaboration	< 8.8.15
Zimbra	Collaboration	8.8.15
Zimbra	Collaboration	9.0.0

References

https://wiki.zimbra.com/wiki/Security_CenterRelease Notes, Vendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23Release Notes, Vendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16Release Notes, Vendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Security_AdvisoriesVendor Advisory
https://wiki.zimbra.com/wiki/Security_CenterRelease Notes, Vendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P23Release Notes, Vendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P16Release Notes, Vendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Security_AdvisoriesVendor Advisory

Timeline

Published: Jul 2, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-34807?

How severe is CVE-2021-34807?

CVE-2021-34807 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.97% probability of exploitation in the next 30 days.

How do I fix CVE-2021-34807?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-34807?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST