MEDIUM 6.5 NVD
CVE-2026-115786
A mailbox quota-accounting vulnerability in Zimbra Collaboration Suite (ZCS) allows an authenticated user to consume another user’s mailbox quota by repeatedly
A mailbox quota-accounting vulnerability in Zimbra Collaboration Suite (ZCS) allows an authenticated user to consume another user’s mailbox quota by repeatedly sharing and revoking a document. Creation of the recipient’s shared-file record charges the document size to mailbox-wide usage. Revocation deletes the record and reverses its folder counters without reversing the mailbox-wide charge. Repeated normal share notifications therefore accumulate quota usage after the visible records are gone. On accounts with a finite quota, this can prevent incoming mail and other size-increasing operations without recipient interaction. The issue affects ZCS 10.1.16 and 10.1.20.
References
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
- https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/
This medium severity vulnerability with a CVSS score of 6.5 was published on 2026-10-23 via NVD.
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