---
id: CVE-2026-90447
title: >-
  A routing rule selects between two different authentication mechanisms for the
  same downstream service based on the value of a client-supplied request
  header, rather than on any property the client cannot control
summary: >-
  A routing rule selects between two different authentication mechanisms for the
  same downstream service based on the value of a client-supplied request
  header, rather than on any property the client cannot control. An
  authenticated user i…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N'
cwe:
  - CWE-290
vendor: CISA
product: Malcolm
affected:
  - Malcolm < v26.06.0
published: '2026-09-11'
updated: '2026-10-02'
sourceUpdated: '2026-10-02T22:16:55.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90447'
references:
  - url: >-
      https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2026/icsa-26-254-01.json
    label: ics-cert@hq.dhs.gov
  - url: 'https://www.cisa.gov/news-events/ics-advisories/icsa-26-254-01'
    label: ics-cert@hq.dhs.gov
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-14T16:14:01.854681Z'
epss: 0.0022
epssPercentile: 0.12484
scores:
  nvd: 6.5
  cna: 7.1
ingestedAt: '2026-09-14T11:11:19.875Z'
---

## Overview

A routing rule selects between two different authentication mechanisms for the same downstream service based on the value of a client-supplied request header, rather than on any property the client cannot control. An authenticated user in possession of a shared service credential can set this header to route around the primary role-based authorization check and reach the alternate path's fixed, elevated role instead. This allows a low-privileged authenticated attacker who knows the shared credential to perform actions reserved for a higher-privileged role.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.