EUVD-2026-277201

fkie_cve-2026-33204

SimpleJWT is a simple JSON web token library written in PHP. Prior to version 1.1.1, an unauthenticated attacker can perform a Denial of Service via JWE header tampering when PBES2 algorithms are used. Applications that call JWE::decrypt() on attacker-controlled JWEs using PBES2 algorithms are affected. This issue has been patched in version 1.1.1.

GHSA-xw36-67f8-339x — SimpleJWT has an Unauthenticated Denial of Service via JWE header tampering

Affected: Packagist: kelvinmo/simplejwt

## Summary

An unauthenticated attacker can perform a Denial of Service via JWE header tampering when PBES2 algorithms are used. Applications that call `JWE::decrypt()` on attacker-controlled JWEs using PBES2 algorithms are affected.

## Details

PHP version: `PHP 8.4.11` SimpleJWT version: `v1.1.0`

The relevant portion of the vulnerable implementation is shown below ([PBES2.php](https://github.com/kelvinmo/simplejwt/blob/edb7807a240b72c59e72d7dca31add9d16555f9f/src/SimpleJWT/Crypt/KeyManagement/PBES2.php)):

```PHP <?php /* ... SNIP ... */ class PBES2 extends BaseAlgorithm implements KeyEncryptionAlgorithm { use AESKeyWrapTrait;

/** @var array<string, mixed> $alg_params */ static protected $alg_params = [ 'PBES2-HS256+A128KW' => ['hash' => 'sha256'], 'PBES2-HS384+A192KW' => ['hash' => 'sha384'], 'PBES2-HS512+A256KW' => ['hash' => 'sha512'] ];

/** @var truthy-string $hash_alg */ protected $hash_alg;

/** @var int $iterations */ protected $iterations = 4096; /* ... SNIP ... */

/** * Sets the number of iterations to use in PBKFD2 key generation. * * @param int $iterations number of iterations * @return void */ public function setIterations(int $iterations) { $this->iterations = $iterations; } /* ... SNIP ... */

/** * {@inheritdoc} */ public function decryptKey(string $encrypted_key, KeySet $keys, array $headers, ?string $kid = null): s…

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EUVD-2026-277201

fkie_cve-2026-33204

GHSA-xw36-67f8-339x — SimpleJWT has an Unauthenticated Denial of Service via JWE header tampering