CVE-2025-66506: Fulcio allocates excessive memory during token parsing

Function identity.extractIssuerURL currently splits (via a call to strings.Split) its argument (which is untrusted data) on periods.

As a result, in the face of a malicious request with an (invalid) OIDC identity token in the payload containing many period characters, a call to extractIssuerURL incurs allocations to the tune of O(n) bytes (where n stands for the length of the function’s argument), with a constant factor of about 16. Relevant weakness: CWE-405: Asymmetric Resource Consumption (Amplification)

Details See identity.extractIssuerURL

Impact Excessive memory allocation