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CVE-2026-117553

7.5, high

Umbraco-CMS Open Redirect Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
7.5, high high CVSS v3.1
EPSS, next 30 days
n/a
Exploitation
No public evidence
Published
27 Oct 2026yesterday

Description

Umbraco CMS before 17.7.2 and 18.2.2 contains an authentication bypass vulnerability that allows unauthenticated attackers to register attacker-controlled OAuth redirect URIs by poisoning the Host header. Attackers send signed-in users authorization links using response_mode=form_post to capture codes, then redeem them via HTTP Basic client credentials to hijack back-office sessions and execute code through Razor templates.

Details

Vendor
Umbraco
Product
Umbraco-CMS
Weakness
CWE-601 (opens in a new tab)
Status
Awaiting analysis
Updated
27 Oct 2026
Assigner
disclosure@vulncheck.com

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

References 5

Patches and fixes 1

Advisories 1

Other references 3

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Beyond this page

Is CVE-2026-117553 in your network?

This page tells you how dangerous CVE-2026-117553 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2026-117553 comes with the devices to patch.

    Learn more about EXYS7600 OCELOT

  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

    Learn more about EXYS7950 KONDRA
Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 28 Oct 2026, not the live upstream state.