CVE-2025-48953: Umbraco-CMS · Unrestricted File Upload
Affects Umbraco-CMSSource CVE Database V5
Not known to be exploited · CVSS 5.5 Medium : upgrade to 16.0.0 or 15.4.2 when convenient.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 16.0.0, 15.4.2
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:LExploitation evidence
Disclosed: evidence found.
CVE published 3 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade umbraco/Umbraco-CMS to 16.0.0 or 15.4.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
GitHubumbraco/Umbraco-CMSpkg:github/umbraco/Umbraco-CMSOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
European organizations should prioritize upgrading Umbraco CMS installations to version 15.4.2 or later immediately to apply the official patch. Until upgrades are completed, organizations should implement strict network segmentation and firewall rules to limit access to the Umbraco CMS administrative interfaces and APIs, reducing exposure to potential attackers. Web application firewalls (WAFs) should be configured to detect and block suspicious file upload patterns and API requests that deviate from normal behavior. Additionally, organizations should enforce multi-factor authentication (MFA) for all CMS users to mitigate the risk posed by low privilege requirements. Regular monitoring and logging of file uploads and API access should be enhanced to detect anomalous activity early. Security teams should conduct thorough audits of uploaded files and scan for known web shells or malicious scripts. Finally, user training to recognize and avoid phishing attempts can reduce the risk of user interaction exploitation.
Description
Umbraco is an ASP.NET content management system (CMS). Starting in version 14.0.0 and prior to versions 15.4.2 and 16.0.0, it's possible to upload a file that doesn't adhere with the configured allowable file extensions via a manipulated API request. The issue is patched in versions 15.4.2 and 16.0.0. No known workarounds are available.