# CVE-2025-66625: Umbraco.Cms — Fixed in 13.12.1 .NET .NET NuGet Not in CISA KEV MEDIUM severity # CVE-2025-66625 — Umbraco.Cms MEDIUM [Fix: umbraco/Umbraco-CMS@7505efd](https://github.com/umbraco/Umbraco-CMS/commit/7505efd433189037f46547932d4a8b603fd4a615) CVE-2025-66625 is a medium-severity (CVSS 4.9) Information Exposure vulnerability in Umbraco.Cms. A fix is available for Umbraco.Cms — see the affected versions and patch details below. Umbraco Vulnerable to Improper File Access and Credential Exposure through Dictionary Import Functionality Also known as[GHSA-hfv2-pf68-m33x](/vulnerability/GHSA-hfv2-pf68-m33x) Published Dec 9, 2025 Updated Oct 28, 2026 Affected 1 pkg Patched 1 / 1 Exploits None indexed Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS) ## Exploitation Status ### No confirmed exploitation observed yet - CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment. Exploitation and automatability from CISA’s SSVC triage for CVE-2025-66625. ## EPSS Exploitation Probability [via FIRST.org ↗](https://www.first.org/epss/) 0.4%probability of exploitation in next 30 days Lower Risk+0.03% Lower risk than most CVEs33th percentile — riskier than 33% of all scored CVEsHighest risk 0.00%0.29%0.59%0.88%0.1%0.4%May 26Sep 26Nov 26 Probability of exploitation in the next 30 days, from [FIRST.org EPSS](https://www.first.org/epss/). ## How urgent is this, really ## Where this sits among everything scored ## Real-World Exposure 1 pkg affected .NET`Umbraco.Cms` Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems. ## Description #### Impact Due to unsafe handling and deletion of temporary files 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 vulnerability does not allow reading or writing file contents. In certain configurations, incomplete clean-up of temporary upload files may additionally expose the NTLM hash of the Windows account running the Umbraco application. The direct impact of this vulnerability is therefore limited to confidentiality, which is reflected in its CVSS base score of 4.9 While the CVSS Base Score captures only the immediate effect, the practical risk varies significantly based on hosting environment and identity configuration. Umbraco Cloud sites run under low-privilege, isolated Azure App Service worker identities, which mitigates the impact of any credential exposure. In contrast, self-hosted deployments could run Umbraco using privileged local or domain accounts. If such an account’s NTLM hash is disclosed, an attacker may be able to: - Perform NTLM relay attacks - Crack the hash offline to recover the underlying password - Authenticate as the compromised identity - Access internal systems trusted by that identity - Move laterally within the network - Potentially escalate to full domain compromise in weakly segmented environments These outcomes are not part of the CVSS base score, which only rates the immediate confidentiality impact, but represent realistic downstream consequences for installations using elevated or widely-trusted service accounts. Self-hosted environments running Umbraco under privileged identities are therefore at significantly higher risk. Vulnerability found and reported by Tomasz Holeksa at Pentest Limited #### Patches The issue has been patched in 13.12.1. #### Workarounds The issue can only be exploited by authorized backoffice accounts with access to the "Translations" section. ## Affected Packages 1 total 1 fixed Ecosystem Package Vulnerable range Fix .NETNuGet `Umbraco.Cms` ≥ 10.0.0&&< 13.12.1 13.12.1`dotnet add package Umbraco.Cms --version 13.12.1` ## Affected Products 1 product · 1 configurations Application `umbraco cms`umbraco ≥ 10.0.0 && < 13.12.1 range ## Detection & mitigation playbook Open-source dependency 1. ### Detect Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Umbraco.Cms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version. 2. ### Fix Update Umbraco.Cms to 13.12.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-66625 is resolved across your whole dependency graph. 3. ### Workarounds Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them. ## Frequently Asked Questions \### Impact Due to unsafe handling and deletion of temporary files 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 vulnerability does not allow reading or writing file contents. In certain configurations, incomplete clean-up of temporary upload files may additionally expose the NTLM hash of the Windows account running the Um O3 Security · Impact-Aware SCA ### Is CVE-2025-66625 in your dependencies? Find it across NuGet, including transitive dependencies. [Scan my dependencies](/book-demo) [How O3 SCA works](/impact-aware-sca)