CVE-2026-115786
A mailbox quota-accounting vulnerability in Zimbra Collaboration Suite (ZCS) allows an…
- Risk score
- 46/100
- CVSS
- 6.5 v3.1
- Exploit chance (30 days)
- 0.4%
- Published
- 23 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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 …
- Affected
- See advisory
- Fix
- Apply the vendor's security update; see the linked advisory.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 6.5 medium
References
Original description
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.
Last activity 23 Oct 2026. Patch Forecast updates every hour.