---
id: CVE-2026-93638
title: >-
  Zimbra Collaboration Suite Pre-Authentication Reflected Cross-Site Scripting
  via Login Page zrememberme Parameter
summary: >-
  A reflected cross-site scripting vulnerability in the login page of Zimbra
  Collaboration Suite (ZCS) allows an unauthenticated attacker to execute
  JavaScript through the zrememberme parameter. A crafted relogin URL selects a
  two-factor e…
severity: medium
cvss: 6.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'
cvssSource: cna
cwe:
  - CWE-79
vendor: Zimbra
product: Zimbra Collaboration Suite
affected:
  - collaboration_suite <= 10.1.17
published: '2026-10-23'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T13:28:03.891Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-93638'
references:
  - url: 'https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories'
  - url: >-
      https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/
tags:
  - cve.org
ingestedAt: '2026-10-23T14:28:08.709Z'
---

## Overview

A reflected cross-site scripting vulnerability in the login page of Zimbra Collaboration Suite (ZCS) allows an unauthenticated attacker to execute JavaScript through the zrememberme parameter. A crafted relogin URL selects a two-factor error display that inserts the parameter into a hidden input attribute without HTML encoding. A victim who opens the URL receives attacker-controlled script and page content under the legitimate Zimbra origin, allowing credential capture through a replacement login form. The relogin path logs out an existing session before rendering the payload, so the demonstrated attack does not inherit that session's mailbox access. ZCS 10.1.16 and 10.1.17 are affected.

## Affected

- `collaboration_suite <= 10.1.17`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.