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CVE-2025-66625: Umbraco is an ASP.NET CMS

25
Routine
MEDIUM 4.9UPGRADE

CVE-2025-66625 is a medium-severity flaw (CVSS 4.9) affecting umbraco cms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Umbraco is an ASP.NET CMS. Due to unsafe handling and deletion of temporary files in versions 10.0.0 through 13.12.0, during the dictionary upload process an attacker with access to the backoffice can trigger predictable requests to temporary file paths. The application’s error responses (HTTP 500 when a file exists, 404 when it does not) allow the attacker to enumerate the existence of arbitrary files on the server’s filesystem. This vulnerabili

Why this priority

  • No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score4.9 (Medium)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededHigh
User interactionNone
EPSS exploit chance0.4% (top 71%)
CISA exploited listNo
WeaknessCWE-200, CWE-377, CWE-552
Published2025-12-09
Last modified2026-10-14
Publisher (CNA): GitHub, Inc. · Vendor: umbraco

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Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

umbraco umbraco cms UPGRADE
Affected: >= 10.0.0 and < 13.12.1
Fixed in: 13.12.1
Safe to downgrade to: a release before 10.0.0
1. Check installed version
apt-cache policy umbraco-cms || rpm -q umbraco-cms || umbraco-cms --version
2. UPGRADE to 13.12.1 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade umbraco-cms
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade umbraco-cms
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
3. If no update is available yet, DOWNGRADE to a release before 10.0.0 (Debian / Ubuntu)
apt-cache madison umbraco-cms sudo apt install umbraco-cms=<VERSION_BEFORE_10.0.0> sudo apt-mark hold umbraco-cms
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list umbraco-cms sudo dnf downgrade umbraco-cms-<VERSION_BEFORE_10.0.0> sudo dnf versionlock add umbraco-cms
Downgrade risk
Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.
After downgrade
Restart the service, and keep the package held until a fixed release ships.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-66625?

umbraco cms: upgrade to 13.12.1. Exact commands for each OS are on this page.

Is CVE-2025-66625 being exploited?

CVE-2025-66625 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-66625 affect?

CVE-2025-66625 affects umbraco cms. Severity is medium (CVSS 4.9). Umbraco is an ASP.NET CMS. Due to unsafe handling and deletion of temporary files in versions 10.0.0 through 13.12.0, during the dictionary upload process an attacker with access to the backoffice can trigger predictable requests to tempora

How urgent is CVE-2025-66625?

Priority 25/100. No elevated risk signals yet.

Software pages

.NET vulnerabilities

Related CVEs

References

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