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GHSA-5739-39v2-5754

GHSA-5739-39v2-5754 · PHP JWT Library: RSA1_5 (RSAES-PKCS1-v1_5) decryption lacks implicit rejection, exposing a Bleichenbacher/Marvin padding oracle

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### Impact `RSACrypt::decryptWithRSA15()` (used by the `RSA1_5` key-encryption algorithm) implements RSAES-PKCS1-v1_5 decryption by inspecting the padding after RSADP and throwing `InvalidArgumentException` as soon as the padding is malformed. It does **not** implement the implicit-rejection countermeasure required by RFC 3447 §7.2.2 / RFC 8017 §7.1.2 (return a deterministic pseudo-random value of the expected length on padding failure and let the downstream step fail uniformly). From a JWE caller this yields a Bleichenbacher/Marvin padding oracle: an attacker submitting adaptively crafted `encrypted_key` values can distinguish (a) padding rejected, (b) padding valid but wrong CEK length, and (c) padding valid and full AEAD executed — even though `JWEDecrypter` returns the same `false` in all cases — because each path performs a measurably different amount of work, amplifiable by enlarging the ciphertext (CWE-208 timing side channel). Enough adaptive queries can recover the wrapped CEK. ### Affected configurations Applications that register `RSA1_5` in their decryption `AlgorithmManager` and hold an RSA private key. ### Patches PKCS#1 v1.5 decryption now performs implicit rejection: on invalid padding (or unexpected recovered length) it returns a random CEK of the expected size selected in constant time, so the full content-decryption (AEAD) step always runs and fails uniformly, removing the observable difference between padding-valid and padding-invalid ciphertexts. Users are still strongly encouraged to migrate to `RSA-OAEP`. ### Workarounds Prefer `RSA-OAEP`/`RSA-OAEP-256`; do not enable `RSA1_5` for untrusted tokens. ### References - RFC 3447 §7.2.2 / RFC 8017 §7.1.2 - Bleichenbacher (1998); Marvin attack - CWE-208: Observable Timing Discrepancy ## Résolution Un correctif a été préparé sur une branche dédiée basée sur `3.4.x`, avec des tests anti-régression dédiés (fork privé temporaire de cette advisory, PR #1). **RSA1_5** — déchiffrement PKCS#1 v1.5 avec *implicit rejection* en temps constant (RFC 3447 §7.2.2) : un padding invalide n'est plus distinguable d'un padding valide, neutralisant l'oracle Bleichenbacher. **Validation :** `php -l` OK, PHPUnit vert, aucune nouvelle erreur PHPStan introduite (différentiel nul vs `3.4.x`), aucun commentaire ajouté dans le code source. Après merge, cascade prévue `3.4.x → 4.0.x → 4.1.x`.

CVSS 6.3 · Media · Corrección disponible

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Pila tecnológica: php

Productos y versiones afectados

  • web-token/jwt-library Packagist

    Versiones
    • 3.3.0
    • 3.3.1
    • 3.3.2
    • 3.3.3
    • 3.3.4
    • 3.3.5
    • 3.4.0
    • 3.4.1
    • 3.4.2
    • 3.4.3
    • 3.4.4
    • 3.4.5
    • 3.4.6
    • 3.4.7
    • 3.4.8
    • 3.4.9
    Intervalos de versiones afectados
    • ECOSYSTEM: < 3.4.10

    Actualiza a 3.4.10

  • web-token/jwt-library Packagist

    Versiones
    • 4.0.0
    • 4.0.1
    • 4.0.2
    • 4.0.3
    • 4.0.4
    • 4.0.5
    • 4.0.6
    Intervalos de versiones afectados
    • ECOSYSTEM: ≥ 4.0.0, < 4.0.7

    Actualiza a 4.0.7

  • web-token/jwt-library Packagist

    Versiones
    • 4.1.0
    • 4.1.1
    • 4.1.2
    • 4.1.3
    • 4.1.4
    • 4.1.5
    • 4.1.6
    Intervalos de versiones afectados
    • ECOSYSTEM: ≥ 4.1.0, < 4.1.7

    Actualiza a 4.1.7

Fuentes originales

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