CVE-2026-42849

Description

authentik is an open-source identity provider. Prior to versions 2025.12.5 and 2026.2.3, due to the implementation of stages in the SFE (Simple Flow Executor) in order to make the interface more compatible with legacy browsers, it was possible to use an XSS exploit in the AutosubmitStage. This issue has been patched in versions 2025.12.5 and 2026.2.3.

CVSS v3.1 Score

9.3

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0032

Probability of exploitation

0.24%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

Affected Products

Vendor	Product	Versions
goauthentik	authentik	< 2025.12.5
goauthentik	authentik	2026.2.0 — 2026.2.3

References

Advisories & Patches

https://github.com/goauthentik/authentik/security/advisories/GHSA-pgff-5mx8-fqj3

Frequently Asked Questions

What is CVE-2026-42849? +

authentik is an open-source identity provider. Prior to versions 2025.12.5 and 2026.2.3, due to the implementation of stages in the SFE (Simple Flow Executor) in order to make the interface more compatible with legacy browsers, it was possible to use an XSS exploit in the AutosubmitStage. This issue has been patched in versions 2025.12.5 and 2026.2.3. It has a CVSS v3.1 base score of 9.3 (CRITICAL).

How severe is CVE-2026-42849? +

CVE-2026-42849 has a CVSS v3.1 score of 9.3 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0032, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-42849? +

CVE-2026-42849 affects products from goauthentik, specifically: authentik. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-42849? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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