---
id: CVE-2025-66514
title: >-
  Nextcloud Mail is the mail app for Nextcloud, a self-hosted productivity
  platform
summary: >-
  Nextcloud Mail is the mail app for Nextcloud, a self-hosted productivity
  platform. Prior to 5.5.3, a stored HTML injection in the Mail app's message
  list allowed an authenticated user to inject HTML into the email subjects.
  Javascript wa…
severity: low
cvss: 3.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N'
cwe:
  - CWE-79
vendor: nextcloud
product: mail
affected:
  - mail < 5.5.3
patched:
  - mail 5.5.3
published: '2025-12-05'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T21:10:00.327'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-66514'
references:
  - url: >-
      https://github.com/nextcloud/mail/commit/c64fcc3b79e0c089b5e1d2e04a07bfa740b2ac09
    label: security-advisories@github.com
  - url: 'https://github.com/nextcloud/mail/pull/11740'
    label: security-advisories@github.com
  - url: >-
      https://github.com/nextcloud/security-advisories/security/advisories/GHSA-v394-8gpc-6fv5
    label: security-advisories@github.com
  - url: 'https://hackerone.com/reports/3357036'
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.0025
epssPercentile: 0.16294
ingestedAt: '2026-10-27T18:12:09.277Z'
---

## Overview

Nextcloud Mail is the mail app for Nextcloud, a self-hosted productivity platform. Prior to 5.5.3, a stored HTML injection in the Mail app's message list allowed an authenticated user to inject HTML into the email subjects. Javascript was correctly blocked by the content security policy of the Nextcloud Server code.

## Affected

- `mail < 5.5.3`

## Remediation

Upgrade past the affected range:

- `mail 5.5.3`