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Fencer Intel
high 8.8

CVE-2026-39910 json

STACKIT IaaS API Privilege Escalation via Service Account Attachment

published 5mo ago modified 10d ago also EUVD-2026-35128

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

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.

Patch / fix

  • STACKIT IaaS API 2026-05-28

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CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
5mo ago

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 4.0 7.7 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
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA 4.0 7.7 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • STACKIT IaaS API

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.