CVE-2024-23647

PKCE downgrade attack in Authentik

HIGH
8.8
CVSS Score
Published: January 30, 2024 at 04:10 PM UTC
Updated: June 17, 2026 at 07:13 AM UTC
1 product affected across 1 vendorAuthentik

Using authentik by goauthentik?

Get instant alerts when new vulnerabilities affect authentik - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
HIGH8.8
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

Authentik is an open-source Identity Provider. There is a bug in our implementation of PKCE that allows an attacker to circumvent the protection that PKCE offers. PKCE adds the code_challenge parameter to the authorization request and adds the code_verifier parameter to the token request. Prior to 2023.8.7 and 2023.10.7, a downgrade scenario is possible: if the attacker removes the code_challenge parameter from the authorization request, authentik will not do the PKCE check. Because of this bug, an attacker can circumvent the protection PKCE offers, such as CSRF attacks and code injection attacks. Versions 2023.8.7 and 2023.10.7 fix the issue.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2023.10.7v < 2023.8.72023.10.0 ≤ v < 2023.10.7
Affected range stops below 2023.10.7, so it looks safe — our inference, not a vendor statement
Affected range stops below 2023.8.7, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-287

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card