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fix(sdk): clear SonarQube ReDoS hotspot in base64url encode #62

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Merged
wolpert merged 1 commit into from
Jun 13, 2026
Merged

fix(sdk): clear SonarQube ReDoS hotspot in base64url encode #62

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8 changes: 6 additions & 2 deletions clients/passkeys-browser/src/base64url.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -15,12 +15,16 @@ export function encode(input: ArrayBuffer | Uint8Array | ArrayBufferView): Base6
for (let i = 0; i < bytes.length; i++) {
s += String.fromCharCode(bytes[i]!);
}
return btoa(s).replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, "");
// base64url per RFC 4648 §5: map +/ to -_ and strip padding. Using replaceAll with
// string literals (no regexes) keeps this linear — it avoids the ReDoS shape
// SonarQube flags on `/=+$/`. `=` only ever appears as trailing base64 padding, so
// removing all of it is equivalent to stripping the trailing run.
return btoa(s).replaceAll("+", "-").replaceAll("/", "_").replaceAll("=", "");
}

export function decode(input: Base64Url): Uint8Array {
const pad = "=".repeat((4 - (input.length % 4)) % 4);
const normalized = input.replace(/-/g, "+").replace(/_/g, "/") + pad;
const normalized = input.replaceAll("-", "+").replaceAll("_", "/") + pad;
const binary = atob(normalized);
const bytes = new Uint8Array(binary.length);
for (let i = 0; i < binary.length; i++) {
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