feat(auth0-express): support session secret rotation - #36
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Widen `sessionSecret` to `string | string[]`. The first secret encrypts new cookies; all secrets are tried, in order, when decrypting — letting you roll the secret without logging existing users out. A comma-separated `AUTH0_SESSION_SECRET` / `SECRET` env var is parsed into an array in the same order. The underlying @auth0/auth0-server-js stores already accept an array secret, so this is a type widening plus env parsing; the required-secret guard now also rejects an empty array.
cschetan77
reviewed
Aug 3, 2026
…itly A programmatically-passed sessionSecret string bypassed comma-separated parsing since the spread of `config` happened after the env-based parse. Mirrors the existing appBaseUrl re-parse.
…n type sessionSecret is a required string | string[] field, so assigning the helper's string | string[] | undefined return type failed to compile. Add an overload so a definite string input is typed to never return undefined.
cschetan77
approved these changes
Aug 3, 2026
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Summary
Adds session secret rotation to
@auth0/auth0-express, so you can roll the session secret without logging existing users out.sessionSecretnow acceptsstring | string[]. The first secret encrypts new cookies; all secrets are tried, in order, when decrypting.AUTH0_SESSION_SECRET(or legacySECRET) is parsed into an array in the same order — matching howAPP_BASE_URLalready handles comma-separated values.Rotation flow
sessionSecret: [newSecret, oldSecret]— new cookies encrypt undernewSecret, existingoldSecretcookies still decrypt.oldSecret.Tests
config.spec.ts— explicit array, comma-separatedAUTH0_SESSION_SECRET, comma-separated legacySECRET, single value stays a string, trailing-comma collapse, empty-array throws.session-secret-rotation.spec.ts(new) — end-to-end viacreateServerClientInstance: a cookie encrypted under the old secret is still readable after rotating to[new, old], and becomes unreadable once the old secret is dropped.All 186 tests pass; lint, typecheck, and build are clean.
Docs
sessionSecretJSDoc intypes.tsdocuments rotation.