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

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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.

Source published

8 Oct 2026 16:25:42 UTC

Source modified

8 Oct 2026 19:10:22 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N