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Fencer Vulns
high 8.6

CVE-2026-54730 json

authentik: Authentication Flow Bypass via Unguarded challenge_valid() in AuthenticatorEndpointGDTCStage and GoogleChromeStageView

published 2026-08-18 2 mo ago modified 2026-10-22 17 d ago also BIT-authentik-2026-54730 , EUVD-2026-61059 , GHSA-3v9h-3hrm-29cx

cvss
8.6
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 52%
public exploits
0
none known

Summary

authentik is an open-source identity provider. Prior to 2026.2.6 and 2026.5.5, the enterprise Google Chrome device-trust stages advance the flow without confirming that the out-of-band device attestation actually ran. Affected enterprise deployments place either a Google Chrome Endpoint stage with mode set to REQUIRED or the deprecated Google Chrome Device Trust Connector stage in an authentication flow. The device attestation occurs in a verification iframe that calls the Google Verified Access API and records the verified device on success, but the vulnerable stages treat the flow as passed as soon as the stage is submitted. An attacker who can reach such a stage, including after primary username and password authentication, can skip the verification iframe and authenticate from a device that was never verified. Where device trust is the only additional factor, that protection is fully bypassed, while other configured factors remain in force. This issue is fixed in versions 2026.2.6 and 2026.5.5.

Patch / fix

  • bitnami authentik 2026.2.6, 2026.5.5
  • goauthentik authentik 2026.2.6, 2026.5.5

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2 mo ago

Exploit prediction

0.68% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 8.6 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CNA 4.0 8.6 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/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 packages

ecosystem package affected fixed in
bitnami authentik
<2026.2.6
>=2026.5.0, <2026.5.5
2026.2.6
2026.5.5

Affected products

  • goauthentik authentik

Classification

Weakness
  • CWE-284 Improper Access Control
  • CWE-807 Reliance on Untrusted Inputs in a Security Decision

References

Sources

Fencer Vulns 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.