---
id: "CVE-2026-10632"
kind: "vulnerability"
aliases: ["CVE-2026-10632"]
title: "Zimbra Collaboration: reflected XSS lets attacker act as logged-in user"
severity: "high"
cvss: 8.7
epss: 0.00424
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["email", "package", "self-hosted", "zimbra"]
not_affected_if: ["managed-hosting", "not-zcs-10.1.16"]
published_at: "2026-10-23T14:17:31+00:00"
first_seen_at: "2026-10-23T21:57:34+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-10632", "first_seen_at": "2026-10-23T21:57:34+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-10632", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Zimbra Collaboration: reflected XSS lets attacker act as logged-in user

The Classic Web Client of Zimbra Collaboration Suite does not HTML-encode the packages parameter of the /h/rest document editor, so injected JavaScript runs in a victim's browser. Combined with CVE-2026-50053, a crafted URL can run script in another signed-in user's session, letting an attacker read mailbox data and act as that user.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

Check the installed ZCS version (su - zimbra -c 'zmcontrol -v'); 10.1.16 is affected.

## Fix

Upgrade Zimbra Collaboration Suite to 10.1.17 or later.

## Timeline

- 2026-10-23T21:57:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-10632
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-10632

## From the sources

A reflected cross-site scripting vulnerability in the Classic Web Client of Zimbra Collaboration Suite (ZCS) allows an attacker to inject JavaScript through the packages parameter of the /h/rest document editor. The editor inserts package names into script attributes without HTML encoding. When combined with CVE-2026-50053, an attacker with an ordinary Zimbra account can supply their own authentication token and document identifiers in a URL and execute JavaScript in another signed-in user's Zimbra browser session when that user opens the URL. This permits reading mailbox data and performing authenticated actions as the victim. The issue affects ZCS 10.1.16 and was remediated in 10.1.17.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_