Unrated severityNVD Advisory· Published Dec 5, 2025· Updated Dec 8, 2025
Nextcloud Mail stored HTML injection in subject text
CVE-2025-66514
Description
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
2- Range: <5.5.3
- nextcloud/security-advisoriesv5Range: >= 5.2.0-beta.1, < 5.5.3
Patches
Vulnerability mechanics
References
4- github.com/nextcloud/mail/commit/c64fcc3b79e0c089b5e1d2e04a07bfa740b2ac09mitrex_refsource_MISC
- github.com/nextcloud/mail/pull/11740mitrex_refsource_MISC
- github.com/nextcloud/security-advisories/security/advisories/GHSA-v394-8gpc-6fv5mitrex_refsource_CONFIRM
- hackerone.com/reports/3357036mitrex_refsource_MISC
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