All vulnerabilities
CVE-2026-50055

Zimbra Collaboration Suite Sieve Notify Filter Action Bypasses Mail Forwarding Restriction via Variable Expansion

Zimbra Zimbra Collaboration SuiteApplications & CMS
Open in ThreatlineRecord JSON
CVSS
6.5Medium
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.27%Chance of exploitation activity in the next 30 days, higher than 18% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in10.1.20Fixed versionCVE List
Published8 Oct 2026Updated 8 Oct 2026CVE List

What fixes it

  • 10.1.20Zimbra Collaboration SuiteCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Timeline

  1. 8 Oct 2026, 16:25 UTCPublishedCVE List
  2. 14 Oct 2026, 13:00 UTCExploit code publicRapid7

Reports 1

1 outlet mention it. Reports are not confirmation; each links to its source.

Description

A policy-enforcement flaw in Zimbra Collaboration Suite allows an authenticated user to bypass disabled mail forwarding by using a Sieve notify action to send copies of email content and headers to an arbitrary address.

Text from CVE List

Affected versions 1

  • Zimbra Collaboration Suiteaffected: all versions before 10.1.20CVE List

References 1