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CVE-2026-115786

Zimbra Collaboration Suite Shared-File Mailbox Quota Accounting Error Enables Quota Exhaustion

Severity
Medium 6.5
Published
23 Oct 2026
Last changed
2 Nov 2026
Added to UpHeron
3 Nov 2026
Sources
NVD, CVE Program

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.…

Affected software

SoftwareAffected versions
Zimbra CollaborationServers and applications · cna:zimbra|zimbra collaboration suite
  • Every version up to 10.1.20
Zimbra CollaborationServers and applications · cpe:a:synacor:zimbra_collaboration_suite
  • Every version up to 10.1.20

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2026-115786
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2026-115786