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web-token/jwt-library: RSACrypt::decryptWithRSA15() now uses implicit rejection to prevent padding oracle attacks

RSACrypt::decryptWithRSA15() now performs implicit rejection on invalid PKCS#1 v1.

19 Jun 2026Read 1 minSeverity: schedule it

What changed

RSACrypt::decryptWithRSA15() now performs implicit rejection on invalid PKCS#1 v1.5 padding, returning a random CEK of expected size in constant time, instead of throwing InvalidArgumentException. This removes the timing side channel that enabled Bleichenbacher/Marvin padding oracle attacks.

Who it affects

Applications that register RSA1_5 in their decryption AlgorithmManager and hold an RSA private key.

What to do today

Update to the patched version as soon as it is released; in the meantime, prefer RSA-OAEP or RSA-OAEP-256 and do not enable RSA1_5 for untrusted tokens.

The trail
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