CVE-2023-28833

Unrestricted filenames for logo or favicon as admin in the theming settings in nextcloud server

HIGH
8.8
CVSS Score
Published: March 30, 2023 at 06:49 PM UTC
Updated: June 17, 2026 at 05:48 AM UTC
1 product affected across 1 vendorNextcloud/server

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Severity
HIGH8.8
Exploit prediction
EPSS 0.8%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

23.0.0 ≤ v < 23.0.1424.0.0 ≤ v < 24.0.1025.0.0 ≤ v < 25.0.4
Affected range stops below 23.0.14, so it looks safe — our inference, not a vendor statement
Affected range stops below 24.0.10, so it looks safe — our inference, not a vendor statement
Affected range stops below 25.0.4, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-22CWE-434

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