Arc Enabled Servers - Azure Connected Machine…: Authentication Bypass Using an Alternate Path or Channel
CVE-2026-26117 is a high-severity authentication bypass using an alternate path or channel vulnerability in Arc Enabled Servers - Azure Connected Machine Agent from Microsoft, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists version 1.61 as the first without the flaw, so updating Arc Enabled Servers - Azure Connected Machine Agent to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.48% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Arc Enabled Servers - Azure Connected Machine Agent to 1.61 or a later version.
- Read the advisory on msrc.microsoft.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Microsoft | Arc Enabled Servers - Azure Connected Machine Agent | 1.0.0 up to, but not including, 1.61 | 1.61 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (microsoft.com).
Official description
Authentication bypass using an alternate path or channel in Azure Windows Virtual Machine Agent allows an authorized attacker to elevate privileges locally.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authentication Bypass Using an Alternate Path or Channel
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
How developers prevent this class of flaw
- Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.
More Authentication Bypass Using an Alternate Path or Channel vulnerabilities (CWE-288)
Timeline
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Recent Authentication Bypass Using an Alternate Path or Channel vulnerabilities
- 7.2 High severity
- 8.8 High severity
- 9.8 Critical severity
- 10.0 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
Spotted an error? Tell us.