GHSA-6vvh-pxr4-25r7: PHP JWT Framework Chacha20Poly1305 Key-encryption Algorithm Discards The Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6vvh-pxr4-25r7",
  "modified" : "2026-06-18T21:08:15Z",
  "published" : "2026-06-18T21:08:15Z",
  "aliases" : [ ],
  "summary" : "PHP JWT Framework: Chacha20Poly1305 key-encryption algorithm discards the Poly1305 authentication tag, performing no authentication on decryption",
  "details" : "### Impact\n\nThe experimental `Chacha20Poly1305` key-encryption algorithm generates the 16-byte Poly1305 authentication tag during `encryptKey()` but **discards it**: the tag is never written to the header and therefore never reaches the wire. On the receiving side, `decryptKey()` calls `openssl_decrypt('chacha20-poly1305', ...)` **without the tag argument**, which makes OpenSSL skip authentication entirely.\n\nAs a result the AEAD construction is silently degraded to unauthenticated ChaCha20: a tampered encrypted CEK is accepted, and because ChaCha20 is a stream cipher, a single-byte change in the ciphertext propagates as a single-byte change in the recovered CEK with no integrity check (CWE-353 / CWE-347). An attacker on the token path can manipulate the wrapped key without detection.\n\n### Affected configurations\n\nApplications that register `Jose\\Experimental\\KeyEncryption\\Chacha20Poly1305` (package `web-token/jwt-experimental`) as a JWE `alg`.\n\n### Patches\n\n`encryptKey()` now publishes the Poly1305 tag as the base64url `tag` header parameter (and asserts it is 16 bytes). `decryptKey()` requires the `tag` header, validates its length, and passes it to `openssl_decrypt()` so the tag is actually verified, in line with RFC 7539 / RFC 8439. Tampering now results in a decryption failure.\n\n> Note: this changes the wire format of tokens produced with this experimental algorithm (a `tag` header is now emitted and required).\n\n### Workarounds\n\nDo not use the experimental `Chacha20Poly1305` key-encryption algorithm for untrusted input until upgraded.\n\n### References\n\n- RFC 7539 / RFC 8439 (ChaCha20-Poly1305 AEAD)\n- CWE-353: Missing Support for Integrity Check\n\n## Résolution\n\nUn 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).\n\n**ChaCha20-Poly1305** — le tag d'authentification Poly1305 est désormais publié dans le header au chiffrement et vérifié au déchiffrement (RFC 7539), rétablissant l'intégrité AEAD.\n\n**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`.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "web-token/jwt-experimental"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "4.1.6"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "web-token/jwt-library"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.4.10"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "web-token/jwt-library"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.0.0"
      }, {
        "fixed" : "4.0.7"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "web-token/jwt-library"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.1.0"
      }, {
        "fixed" : "4.1.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/web-token/jwt-framework/security/advisories/GHSA-6vvh-pxr4-25r7"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/web-token/jwt-library/GHSA-6vvh-pxr4-25r7.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/web-token/jwt-framework"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-347", "CWE-353" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-18T21:08:15Z",
    "nvd_published_at" : null
  }
}