diff --git a/FirebaseAuth/CHANGELOG.md b/FirebaseAuth/CHANGELOG.md
index 9a878b35ca7..8940131c5c3 100644
--- a/FirebaseAuth/CHANGELOG.md
+++ b/FirebaseAuth/CHANGELOG.md
@@ -1,4 +1,5 @@
 # Unreleased
+- [fixed] Fix Multi-factor session crash on second Firebase app. (#14238)
 - [fixed] Updated most decoders to be consistent with Firebase 10's behavior
   for decoding `nil` values. (#14212)
 
diff --git a/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactor.swift b/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactor.swift
index c60f353e362..5b1675fdfa0 100644
--- a/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactor.swift
+++ b/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactor.swift
@@ -34,7 +34,7 @@ import Foundation
     /// operation.
     @objc(getSessionWithCompletion:)
     open func getSessionWithCompletion(_ completion: ((MultiFactorSession?, Error?) -> Void)?) {
-      let session = MultiFactorSession.sessionForCurrentUser
+      let session = MultiFactorSession.session(for: user)
       if let completion {
         completion(session, nil)
       }
diff --git a/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactorSession.swift b/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactorSession.swift
index 42067fd30c3..c4bda3eba36 100644
--- a/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactorSession.swift
+++ b/FirebaseAuth/Sources/Swift/MultiFactor/MultiFactorSession.swift
@@ -39,8 +39,9 @@ import Foundation
     /// Current user object.
     var currentUser: User?
 
-    class var sessionForCurrentUser: MultiFactorSession {
-      guard let currentUser = Auth.auth().currentUser else {
+    class func session(for user: User?) -> MultiFactorSession {
+      let currentUser = user ?? Auth.auth().currentUser
+      guard let currentUser else {
         fatalError("Internal Auth Error: missing user for multifactor auth")
       }
       return .init(idToken: currentUser.tokenService.accessToken, currentUser: currentUser)