What’s Vulnerable › Vulnerabilities

CVE-2023-48302: Nextcloud Server vulnerable to Self XSS when pasting HTML into Text app with Ctrl+Shift+V

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-11-21 · updated 2026-06-17
• Weakness: CWE-79

Description

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.13, 26.0.8, and 27.1.3 of Nextcloud Server and Nextcloud Enterprise Server, when a user is tricked into copy pasting HTML code without markup (Ctrl+Shift+V) the markup will actually render. Nextcloud Server and Nextcloud Enterprise Server versions 25.0.13, 26.0.8, and 27.1.3 contain a fix for this issue. As a workaround, disable app text.

Affected products

• Nextcloud Server: from 25.0.0 before 25.0.13; from 26.0.0 before 26.0.8; from 27.0.0 before 27.1.3 — fixed in 25.0.13, 26.0.8, 27.1.3

How to fix

Upgrade to a fixed version: Nextcloud Server 25.0.13, 26.0.8, 27.1.3. Check the vendor advisory for mitigations.

References

• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-p7g9-x25m-4h87
• https://github.com/nextcloud/text/pull/4877
• https://hackerone.com/reports/2211561
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-p7g9-x25m-4h87
• https://github.com/nextcloud/text/pull/4877
• https://hackerone.com/reports/2211561

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