# CVE-2026-50055 — Zimbra Collaboration Suite

> As of 2026-10-08, CVE-2026-50055 is a MEDIUM-severity vulnerability in Zimbra Collaboration Suite, CVSS v3.1 6.5, EPSS 0.2% (18.2th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-50055, most recently “Zimbra Collaboration Suite 10.1.20 Patches Critical Unauthenticated SNMP/Swatchdog Command Injection Plus Six Additional CVEs”.

**Last updated:** 2026-10-08

## What is CVE-2026-50055?

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.

The record classifies CVE-2026-50055 under weakness class [CWE-863](https://intel.threadlinqs.com/cwe/CWE-863). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs no user interaction, and has high impact on confidentiality. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 4 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 6.5 — MEDIUM (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **EPSS (FIRST):** 0.2% probability of exploitation in the next 30 days, higher than 18.2% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-10-08

## Is CVE-2026-50055 being exploited?

Weaponised exploit code for CVE-2026-50055 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 47 in the Threadlinqs vulnerability feed.

- [HORKimhab/CVE-2026-50055](https://github.com/HORKimhab/CVE-2026-50055) (github)

## Affected products and versions

- [Zimbra](https://intel.threadlinqs.com/vendors/zimbra): Collaboration Suite

## How to fix CVE-2026-50055

No vendor patch reference has been recorded for CVE-2026-50055 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-50055

1 tracked threat in the Threadlinqs corpus references CVE-2026-50055, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Zimbra Collaboration Suite 10.1.20 Patches Critical Unauthenticated SNMP/Swatchdog Command Injection Plus Six Additional CVEs](https://intel.threadlinqs.com/threat/TL-2026-1586) — CRITICAL · 2026-07-21

## Sources

Enriched from CVE.org, FIRST EPSS, public proof-of-concept repositories. Last verified by Threadlinqs on 2026-10-10.

**Vendor advisory and patch**

- [wiki.zimbra.com — vendor advisory](https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-50055
Full detection coverage and IOCs for threats exploiting CVE-2026-50055 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp