What’s Vulnerable › Vulnerabilities

CVE-2023-28833: Unrestricted filenames for logo or favicon as admin in the theming settings in nextcloud server

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-03-30 · updated 2026-06-17
• Weakness: CWE-22

Description

Nextcloud server is an open source home cloud implementation. In affected versions admins of a server were able to upload a logo or a favicon and to provided a file name which was not restricted and could overwrite files in the appdata directory. Administrators may have access to overwrite these files by other means but this method could be exploited by tricking an admin into uploading a maliciously named file. It is recommended that the Nextcloud Server is upgraded to 24.0.10 or 25.0.4. Users unable to upgrade should avoid ingesting logo files from untrusted sources.

Affected products

• Nextcloud Server: from 23.0.0 before 23.0.14; from 24.0.0 before 24.0.10; from 25.0.0 before 25.0.4 — fixed in 23.0.14, 24.0.10, 25.0.4

How to fix

Upgrade to a fixed version: Nextcloud Server 23.0.14, 24.0.10, 25.0.4. Check the vendor advisory for mitigations.

References

• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-ch7f-px7m-hg25
• https://github.com/nextcloud/server/pull/36095
• https://github.com/nextcloud/security-advisories/security/advisories/GHSA-ch7f-px7m-hg25
• https://github.com/nextcloud/server/pull/36095

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