How severe is CVE-2026-40172?

CVE-2026-40172 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.

Is CVE-2026-40172 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-40172?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-40172 have an EU (EUVD) identifier?

Yes. CVE-2026-40172 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31489.

When was CVE-2026-40172 published?

CVE-2026-40172 was published on 2026-05-22 and last updated on 2026-06-17.

CVE-2026-40172

CVE-2026-40172 is a high-severity vulnerability with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-269.

Key facts

Severity: High (CVSS 3.x base score 8.1)
EPSS exploit prediction: 0% (31st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-31489
Weakness: CWE-269
Published: 2026-05-22
Last modified: 2026-06-17

Description

authentik is an open-source identity provider. In versions prior to 2025.12.5 and 2026.2.0-rc1 through 2026.2.2, the PATCH /api/v3/core/users/{pk}/ API allows a caller with change_user on a target user to assign arbitrary groups through UserSerializer, including groups with is_superuser=True, without requiring enable_group_superuser, leading to privilege escalation. This bypasses the stricter permission model enforced in group-management paths and enables delegated user-management permissions to escalate target users to administrator-equivalent privilege. Users with permissions to update groups or permissions to update users are able to add themselves or other users they have permissions on to users which have superuser permissions. This issue has been fixed in versions 22025.12.5 and 2026.2.3.

Frequently asked questions

What is CVE-2026-40172?: authentik is an open-source identity provider. In versions prior to 2025.12.5 and 2026.2.0-rc1 through 2026.2.2, the PATCH /api/v3/core/users/{pk}/ API allows a caller with change_user on a target user to assign arbitrary groups through UserSerializer, including groups with is_superuser=True, without requiring enable_group_superuser, leading to privilege escalation. This bypasses the stricter permission model enforced in group-management paths and enables delegated user-management permissions to escalate target users to administrator-equivalent privilege. Users with permissions to update groups or permissions to update users are able to add themselves or other users they have permissions on to users which have superuser permissions. This issue has been fixed in versions 22025.12.5 and 2026.2.3.
How severe is CVE-2026-40172?: CVE-2026-40172 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability high.
Is CVE-2026-40172 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-40172?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-40172 have an EU (EUVD) identifier?: Yes. CVE-2026-40172 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31489.
When was CVE-2026-40172 published?: CVE-2026-40172 was published on 2026-05-22 and last updated on 2026-06-17.

References

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