CVE-2026-93639

A missing authorization vulnerability in Zimbra Collaboration Suite (ZCS) allows a delegated administrator with no explicit administrative grants to overwrite global Zimlet configuration through ConfigureZimletRequest. The uploaded configuration can also add an attacker-controlled domain to the proxy allowlist of the default class of service. If a signed-in user in that class opens a crafted /service/proxy URL, Zimbra serves attacker-controlled HTML under its own origin. The resulting JavaScript can read mailbox data and perform authenticated actions as the victim. Exploitation requires a delegated-administrator account and access to the admin SOAP service; the browser compromise additionally requires the victim to open the crafted URL. ZCS 10.1.16 and 10.1.20 are affected.

CVSS 3.1

8.7CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

EPSS

0.4% chance of exploitation in the next 30 days; higher than 31% of CVEs (scores of 2026-10-25)

CWE

CWE-862

Published

2026-10-23

Modified

2026-10-23

Record from

the NVD, synced 2026-10-24

References

• https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
• https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/

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