28860310413

Committed 07 Jul 2026 10:44AM UTC coverage: 83.048% (+0.06%) from 82.988%

Build # 28860310413

Build Type

push

github

Committed by

web-flow

Commit Message

fix(auth): harden RSA JWK verification against malformed keys (#1079)

Two defects in the RS256 getClaims verification path:
- JWTAlgorithm force-unwrapped JWK.rsaPublishKey, which is nil for a
  malformed key, crashing the process on attacker/network-controlled
  JWKS. Guard it and fall back to server verification.
- The DER length encoder filtered out ALL zero bytes instead of only
  leading zeros, corrupting the length for content of size 256/512/etc.
  Drop only leading zeros of the big-endian length.

Coverage Stats

5 of 6 new or added lines in 2 files covered. (83.33%)

7804 of 9397 relevant lines covered (83.05%)

37.1 hits per line

Source File
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50.0

/Sources/Auth/Internal/JWTAlgorithm.swift

//
//  JWTVerifier.swift
//  Supabase
//
//  Created by Claude on 06/10/25.
//

import Foundation

enum JWTAlgorithm: String {
  case rs256 = "RS256"

  func verify(
    jwt: DecodedJWT,
    jwk: JWK
  ) -> Bool {
    let message = "\(jwt.raw.header).\(jwt.raw.payload)".data(using: .utf8)!
    switch self {
    case .rs256:
      #if canImport(Security)
        guard let publicKey = jwk.rsaPublishKey else { return false }
        return SecKeyVerifySignature(
          publicKey,
          .rsaSignatureMessagePKCS1v15SHA256,
          message as CFData,
          jwt.signature as CFData,
          nil
        )
      #else
        return false
      #endif
    }
  }
}

1	//
2	// JWTVerifier.swift
3	// Supabase
4	//
5	// Created by Claude on 06/10/25.
6	//
7
8	import Foundation
9
10	enum JWTAlgorithm: String {
11	case rs256 = "RS256"
12
13	func verify(
14	jwt: DecodedJWT,
15	jwk: JWK
16	) -> Bool {	1✔
17	let message = "\(jwt.raw.header).\(jwt.raw.payload)".data(using: .utf8)!	1✔
18	switch self {	1✔
19	case .rs256:	1✔
20	#if canImport(Security)
21	guard let publicKey = jwk.rsaPublishKey else { return false }	1✔
22	return SecKeyVerifySignature(	×
NEW 23	publicKey,	×
24	.rsaSignatureMessagePKCS1v15SHA256,	×
25	message as CFData,	×
26	jwt.signature as CFData,	×
27	nil	×
28	)	×
29	#else
30	return false
31	#endif
32	}	1✔
33	}	1✔
34	}

supabase / supabase-swift / 28860310413

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