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Add ability to extract custom claims from the JWT during authentication #431

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Merged
gjtorikian merged 1 commit into from
Feb 4, 2026
Merged

Add ability to extract custom claims from the JWT during authentication #431

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7 changes: 5 additions & 2 deletions lib/workos/session.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -30,9 +30,10 @@ def initialize(user_management:, client_id:, session_data:, cookie_password:)

# Authenticates the user based on the session data
# @param include_expired [Boolean] If true, returns decoded token data even when expired (default: false)
# @param block [Proc] Optional block to call to extract additional claims from the decoded JWT
# @return [Hash] A hash containing the authentication response and a reason if the authentication failed
# rubocop:disable Metrics/AbcSize, Metrics/PerceivedComplexity
def authenticate(include_expired: false)
def authenticate(include_expired: false, &claim_extractor)
return { authenticated: false, reason: 'NO_SESSION_COOKIE_PROVIDED' } if @session_data.nil?

begin
Expand All @@ -59,7 +60,7 @@ def authenticate(include_expired: false)
return { authenticated: false, reason: 'INVALID_JWT' } if expired && !include_expired

# Return full data for valid tokens or when include_expired is true
{
result = {
authenticated: !expired,
session_id: decoded['sid'],
organization_id: decoded['org_id'],
Expand All @@ -72,6 +73,8 @@ def authenticate(include_expired: false)
impersonator: session[:impersonator],
reason: expired ? 'INVALID_JWT' : nil,
}
result.merge!(claim_extractor.call(decoded)) if block_given?
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@greptile-apps greptile-apps bot Feb 4, 2026

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[P0] merge! will raise if the block returns a non-Hash (including nil), which then gets caught by the generic rescue StandardError and turned into { authenticated: false, reason: e.message }. This makes the new block API brittle and can unexpectedly fail authentication for otherwise-valid sessions if a caller forgets to return a hash.

Consider treating nil as “no extra claims” and validating the return type before merging.

Prompt To Fix With AI 
This is a comment left during a code review.
Path: lib/workos/session.rb
Line: 76:76

Comment:
[P0] `merge!` will raise if the block returns a non-Hash (including `nil`), which then gets caught by the generic `rescue StandardError` and turned into `{ authenticated: false, reason: e.message }`. This makes the new block API brittle and can unexpectedly fail authentication for otherwise-valid sessions if a caller forgets to return a hash.

Consider treating `nil` as “no extra claims” and validating the return type before merging.

How can I resolve this? If you propose a fix, please make it concise.

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[P1] The block’s returned hash can overwrite core fields like :authenticated, :session_id, :organization_id, and :reason because merge! prefers the block’s keys. If consumers pass through untrusted logic or make a mistake, this can produce inconsistent or misleading auth results.

A safer pattern is to merge under a dedicated key (e.g. :custom_claims) or explicitly reject/ignore collisions with reserved keys.

Prompt To Fix With AI 
This is a comment left during a code review.
Path: lib/workos/session.rb
Line: 76:76

Comment:
[P1] The block’s returned hash can overwrite core fields like `:authenticated`, `:session_id`, `:organization_id`, and `:reason` because `merge!` prefers the block’s keys. If consumers pass through untrusted logic or make a mistake, this can produce inconsistent or misleading auth results.

A safer pattern is to merge under a dedicated key (e.g. `:custom_claims`) or explicitly reject/ignore collisions with reserved keys.

How can I resolve this? If you propose a fix, please make it concise.

result
rescue JWT::DecodeError
{ authenticated: false, reason: 'INVALID_JWT' }
rescue StandardError => e
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23 changes: 23 additions & 0 deletions spec/lib/workos/session_spec.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -222,6 +222,29 @@
})
end

it 'merges custom claims from claim_extractor block' do
custom_payload = payload.merge(custom_claim: 'custom_value', another_claim: 123)
custom_access_token = JWT.encode(custom_payload, jwk.signing_key, jwk[:alg], { kid: jwk[:kid] })
custom_session_data = WorkOS::Session.seal_data({
access_token: custom_access_token,
user: 'user',
impersonator: 'impersonator',
}, cookie_password,)
session = WorkOS::Session.new(
user_management: user_management,
client_id: client_id,
session_data: custom_session_data,
cookie_password: cookie_password,
)
allow_any_instance_of(JWT::Decode).to receive(:verify_signature).and_return(true)
result = session.authenticate do |jwt|
{ my_custom_claim: jwt['custom_claim'], my_other_claim: jwt['another_claim'] }
end
expect(result[:authenticated]).to be true
expect(result[:my_custom_claim]).to eq('custom_value')
expect(result[:my_other_claim]).to eq(123)
end

describe 'with entitlements' do
let(:payload) do
{
Expand Down