What’s Vulnerable › Vulnerabilities

CVE-2023-48228: OAuth2: PKCE can be fully circumvented

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2023-11-21 · updated 2026-06-17
• Weakness: CWE-287

Description

authentik is an open-source identity provider. When initialising a oauth2 flow with a `code_challenge` and `code_method` (thus requesting PKCE), the single sign-on provider (authentik) must check if there is a matching and existing `code_verifier` during the token step. Prior to versions 2023.10.4 and 2023.8.5, authentik checks if the contents of `code_verifier` is matching only when it is provided. When it is left out completely, authentik simply accepts the token request with out it; even when the flow was started with a `code_challenge`. authentik 2023.8.5 and 2023.10.4 fix this issue.

Affected products

• goauthentik authentik: before 2023.8.5; from 2023.10.0 before 2023.10.4 — fixed in 2023.10.4, 2023.8.5

How to fix

Upgrade to a fixed version: goauthentik authentik 2023.10.4, 2023.8.5. Check the vendor advisory for mitigations.

References

• https://github.com/goauthentik/authentik/blob/dd4e9030b4e667d3720be2feda24c08972602274/authentik/providers/oauth2/views/token.py#L225
• https://github.com/goauthentik/authentik/commit/3af77ab3821fe9c7df8055ba5eade3d1ecea03a6
• https://github.com/goauthentik/authentik/commit/6b9afed21f7c39f171a4a445654cfe415bba37d5
• https://github.com/goauthentik/authentik/commit/b88e39411c12e3f9e04125a7887f12354f760a14
• https://github.com/goauthentik/authentik/pull/7666
• https://github.com/goauthentik/authentik/pull/7668
• https://github.com/goauthentik/authentik/pull/7669
• https://github.com/goauthentik/authentik/releases/tag/version%2F2023.10.4
• https://github.com/goauthentik/authentik/releases/tag/version%2F2023.8.5
• https://github.com/goauthentik/authentik/security/advisories/GHSA-fm34-v8xq-f2c3
• https://github.com/goauthentik/authentik/blob/dd4e9030b4e667d3720be2feda24c08972602274/authentik/providers/oauth2/views/token.py#L225
• https://github.com/goauthentik/authentik/commit/3af77ab3821fe9c7df8055ba5eade3d1ecea03a6

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