Stored HTML Injection Vulnerability in Nextcloud Mail App
CVE-2025-66514

3.5LOW

Key Information:

Vendor

Nextcloud
Status
Security-advisories
Vendor
CVE Published:
5 December 2025

What is CVE-2025-66514?

Nextcloud Mail, the mailing application for the Nextcloud productivity suite, contains a vulnerability that permits authenticated users to inject HTML into the email subjects within the message list. Although JavaScript injections are prohibited by Nextcloud's content security policy, the capacity to manipulate HTML can result in unexpected behaviors or lead to phishing attempts. This issue affects versions of Nextcloud Mail prior to 5.5.3, necessitating an update to mitigate potential risks associated with this vulnerability.

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Deploy the Patch

Affected Version(s)

security-advisories >= 5.2.0-beta.1, < 5.5.3

References

https://github.com/nextcloud/security-advisories/security...
x_refsource_CONFIRM
https://github.com/nextcloud/mail/pull/11740
x_refsource_MISC
https://github.com/nextcloud/mail/commit/c64fcc3b79e0c089...
x_refsource_MISC

CVSS V3.1

Score:
3.5
Severity:
LOW
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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