OpenClaw before 2026.4.2 reuses the PKCE verifier as the OAuth state parameter in the Gemini OAuth flow, exposing it through the redirect URL. Attackers who capture the redirect URL can obtain both the authorization code and PKCE verifier, defeating PKCE protection and enabling token redemption.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
None
No privileges needed
User Interaction
Passive
Minimal interaction
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
None
No data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
References 3
https://github.com/openclaw/openclaw/commit/a26f4d0f3ef0757db6c6c40277cc06a5de7…
disclosure@vulncheck.com
https://github.com/openclaw/openclaw/security/advisories/GHSA-9jpj-g8vv-j5mf
disclosure@vulncheck.com
https://www.vulncheck.com/advisories/openclaw-pkce-verifier-exposure-via-oauth-…
disclosure@vulncheck.com