CVE-2026-115786: Zimbra Collaboration Suite Shared-File Mailbox Quota Accounting Error Enables Quota Exhaustion
Zimbra · Zimbra Collaboration Suite
Vendor fix available · Affected: Zimbra Collaboration Suite · Exploitation: not established
ExploitationNot established
Not in CISA KEV as of catalogue 2026.11.13 (13 Nov)
- In CISA KEV: not seen
- Exploited (reported): not seen
- Scanning observed: not seen
- Proof of concept public: not seen
- Not establishedNothing in the sources we check
Higher than 32% of scored CVEs
Not scored yet. NVD has not published a CVSS score.
DescriptionNVD
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.
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- Zimbra
- Published
- October 2026
Coverage1 article · 1 outlet
First in our coverage: SecurityOnline, 27 Oct.
- Rapid7 Discloses 17 Flaws in Zimbra Collaboration SuiteSecurityOnline · first in our coverage · mentions it in passing
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