Live Exposure Defense: From CVE to Confirmed Exposure in 12 Hours – See more

Back
New CVE Detected

CVE-2026-59309 – Authentication Bypass – VMware vCenter Server 8.0, 9.0.x, 9.1.x

Be the first to know when new zero-days emerge:

Subscribe to Email Alerts
Subscribe to RSS Feed

Summary

CVE-2026-59309 is a critical authentication bypass vulnerability in the VMware Directory Service component of VMware vCenter Server, disclosed by Broadcom on July 29, 2026 as part of advisory VMSA-2026-0006. With a CVSS score of 9.8, a malicious actor with only network access to vCenter can bypass authentication entirely and gain unauthorized access to the system — no credentials, no user interaction, and no elevated privileges required. Broadcom lists no workarounds; patching is the only remediation.

Technical details

  • Root cause: A flaw in the VMware Directory Service (vmdir), the identity and authentication infrastructure underpinning vCenter Single Sign-On, allows authentication controls to be circumvented without valid credentials.
  • Trigger conditions: An attacker only needs network access to a vulnerable vCenter instance. No existing account, configuration dependency, or user action is required to trigger the vulnerability.
  • Attack vector: Remote, unauthenticated, over the network (AV:N/AC:L/PR:N/UI:N). The attack complexity is low and no privileges are required, placing this in the highest-risk tier for network-exposed management infrastructure.
  • Impact: Successful exploitation grants unauthorized access to the vCenter management plane, providing an attacker with significant control over the virtualized environment, its virtual machines, and connected workloads. The CVSS confidentiality, integrity, and availability impact ratings are all HIGH.

Affected software

  • VMware vCenter Server 8.0 (all versions prior to 8.0 Update 3k, build 25600417)
  • VMware vCenter Server 9.0.x (all versions prior to 9.0.2.0100)
  • VMware vCenter Server 9.1.x (all versions prior to 9.1.0.0300)
  • VMware Cloud Foundation 5.x (requires async patch to vCenter 8.0 Update 3k)
  • VMware vSphere Foundation 9.0.x / 9.1.x
  • VMware Telco Cloud Platform 3.0, 4.x, 5.0.x, 5.1.x
  • VMware Telco Cloud Infrastructure 3.0

Severity

  • CVSS v3.1 Base Score: 9.8 (Critical)
  • Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Mitigation and recommended actions

  • Patch immediately:
    • vCenter Server 8.0 → upgrade to 8.0 Update 3k (build 25600417)
    • vCenter Server 9.0.x → upgrade to 9.0.2.0100
    • vCenter Server 9.1.x → upgrade to 9.1.0.0300
    • Cloud Foundation 5.x → apply the async patch to vCenter 8.0 Update 3k
  • No workarounds exist. Broadcom has explicitly confirmed there are no technical workarounds for this vulnerability. Network segmentation and restricting direct internet exposure of vCenter reduce the attack surface but do not substitute for applying the patch.

IONIX Status

The IONIX research team is tracking ongoing exploitation attempts and recommends immediate patching. Potentially affected assets are outlined in this post.

References

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report

How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report
Close

Subscribe to Threat Center RSS

Copy/paste the link below into your preferred RSS reader or follow these instructions to subscribe to Slack alerts.

Open RSS feedSlack setup instructions

Close

Get Real-Time CVE Alerts to Your Email

Be the first to know when new zero-days emerge