CVE-2023-28833Network attack vector

Admin-assisted appdata overwrite via unrestricted upload key

Published Mar 30, 2023 · Updated Feb 11, 2025

Path traversal in Nextcloud Server before 24.0.10 and 25.0.0 through 25.0.3 allows attackers to overwrite appdata files. The ThemingController uploadImage method accepted the request key as a storage filename without checking it against permitted theme-image keys. Exploitation requires an administrator to upload a crafted logo or favicon; the overwrite can interrupt service, while Nextcloud reports no added privilege because administrators already possess code-execution capability.

CVSS severity2.4
Low
EPSS probability0.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Path traversal in Nextcloud Server before 24.0.10 and 25.0.0 through 25.0.3 allows attackers to overwrite appdata files. The ThemingController uploadImage method accepted the request key as a storage filename without checking it against permitted theme-image keys. Exploitation requires an administrator to upload a crafted logo or favicon; the overwrite can interrupt service, while Nextcloud reports no added privilege because administrators already possess code-execution capability.

The record

CVE
CVE-2023-28833
Published
Mar 30, 2023
Updated
Feb 11, 2025
Vendor
Nextcloud GmbH
Product
Security Advisories
Classifications
CWE-22, CWE-434, CWE-657, T1204.002
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Mar 30, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 11, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 24.0.10
  2. Affected versionversion=>= 25.0.0, < 25.0.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Nextcloud GmbH · Security Advisoriesversion=< 24.0.10; version=>= 25.0.0, < 25.0.4

Published CVSS scores

2.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:N/A:L
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-434Unrestricted Upload of File with Dangerous Type
CWE-657Violation of Secure Design Principles
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo