---
id: "CVE-2026-112353"
kind: "vulnerability"
aliases: ["CVE-2026-112353"]
title: "Kerio Connect Webmail: stored XSS via SVG attachment steals sessions"
severity: "high"
cvss: 8.2
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["email", "kerio-connect", "package", "self-hosted", "webmail"]
not_affected_if: ["patched-version"]
published_at: "2026-10-27T17:16:58+00:00"
first_seen_at: "2026-10-27T17:32:45+00:00"
updated_at: "2026-10-27T17:34:29+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-112353", "first_seen_at": "2026-10-27T17:32:45+00:00"}]
---

# Kerio Connect Webmail: stored XSS via SVG attachment steals sessions

Kerio Connect before 10.0.8 Patch 2 lets a remote attacker upload an SVG email attachment with event-handler code that bypasses sanitization. When a victim opens the attachment, the script runs in their authenticated Webmail session and can steal credentials and mailbox contents.

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

## How to check

- Check the installed Kerio Connect version in the admin console or on the server; versions before `10.0.8 Patch 2` are affected
- unknown

## Fix

- Upgrade Kerio Connect to `10.0.8 Patch 2` or later
- Until patched, unknown

## Timeline

- 2026-10-27T17:32:45+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-112353

## From the sources

GFI KerioConnect (Kerio Connect) before 10.0.8 Patch 2 contains a stored cross-site scripting vulnerability in the Webmail component that allows a remote attacker to run JavaScript in a victim's authenticated Webmail session by uploading a crafted SVG email attachment that bypasses sanitization of event-handler attributes. Attackers can exploit the temporary-download endpoint's insufficient Content-Security-Policy sandbox to execute scripts when the attachment is opened, enabling theft of the victim's credentials and mailbox contents. Proofpoint Threat Research has observed exploitation in the wild as a credential and mailbox stealer.

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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_