Affected: Homebrew: ansible@10

### Summary

`pkcs7_decrypt_der`, `pkcs7_decrypt_pem`, and `pkcs7_decrypt_smime` reported the outcome of decrypting a `RecipientInfo`'s `encryptedKey` in several distinguishable ways, one of which disclosed the exact length recovered from the RSA operation. The same distinction was also observable by timing. An application that decrypts attacker-supplied `EnvelopedData` and reflects the outcome gives the attacker a Bleichenbacher oracle against the content-encryption key.

Introduced in 44.0.0. Fixed in 50.0.0.

### Details

Decryption ran as: RSA PKCS#1 v1.5 decrypt of `encryptedKey` → build an AES cipher from the result → AES-CBC decrypt and PKCS#7 unpad. Each stage failed differently, with no RFC 3218 mitigation:

1. invalid RSA padding → `Decryption failed` 2. valid padding, bad key length → `Invalid key size (N) for AES.`, disclosing `N` 3. correct length, wrong key → `Invalid padding bytes.` 4. the real key → plaintext

Case 1 is reachable only where the linked library lacks implicit rejection: OpenSSL 3.0 and 3.1, LibreSSL, and BoringSSL. On OpenSSL 3.2+, used in our wheels, invalid padding instead returns a synthetic plaintext of pseudorandom length, so the error channel does not distinguish conforming ciphertexts.

Exploitation requires a service that auto-decrypts untrusted `EnvelopedData` matching the victim certificate and answers adaptively at high volume, such as an S/MIME gateway or mail filter.

### Fix

Per RFC 3218, the content-encryption algorithm is now r…

Affected: pyca cryptography

cryptography is a package designed to expose cryptographic primitives and recipes to Python developers. From 44.0.0 until 50.0.0, pkcs7_decrypt_der, pkcs7_decrypt_pem, and pkcs7_decrypt_smime reported the outcome of decrypting a RecipientInfo's encryptedKey in several distinguishable ways, one of which disclosed the exact length recovered from the RSA operation. The same distinction was also observable by timing. An application that decrypts attacker-supplied EnvelopedData and reflects the outcome gives the attacker a Bleichenbacher oracle against the content-encryption key. Decryption ran as RSA PKCS#1 v1.5 decrypt of encryptedKey, build an AES cipher from the result, then AES-CBC decrypt and PKCS#7 unpad. Invalid RSA padding, a valid padding with a bad key length, a correct length with a wrong key, and the real key each failed or succeeded differently. Case 1 is reachable only where the linked library lacks implicit rejection: OpenSSL 3.0 and 3.1, LibreSSL, and BoringSSL. Exploitation requires a service that auto-decrypts untrusted EnvelopedData matching the victim certificate and answers adaptively at high volume, such as an S/MIME gateway or mail filter. This issue is fixed in 50.0.0.

Affected: PyPI: cryptography

### Summary

`pkcs7_decrypt_der`, `pkcs7_decrypt_pem`, and `pkcs7_decrypt_smime` reported the outcome of decrypting a `RecipientInfo`'s `encryptedKey` in several distinguishable ways, one of which disclosed the exact length recovered from the RSA operation. The same distinction was also observable by timing. An application that decrypts attacker-supplied `EnvelopedData` and reflects the outcome gives the attacker a Bleichenbacher oracle against the content-encryption key.

Introduced in 44.0.0. Fixed in 50.0.0.

### Details

Decryption ran as: RSA PKCS#1 v1.5 decrypt of `encryptedKey` → build an AES cipher from the result → AES-CBC decrypt and PKCS#7 unpad. Each stage failed differently, with no RFC 3218 mitigation:

1. invalid RSA padding → `Decryption failed` 2. valid padding, bad key length → `Invalid key size (N) for AES.`, disclosing `N` 3. correct length, wrong key → `Invalid padding bytes.` 4. the real key → plaintext

Case 1 is reachable only where the linked library lacks implicit rejection: OpenSSL 3.0 and 3.1, LibreSSL, and BoringSSL. On OpenSSL 3.2+, used in our wheels, invalid padding instead returns a synthetic plaintext of pseudorandom length, so the error channel does not distinguish conforming ciphertexts.

Exploitation requires a service that auto-decrypts untrusted `EnvelopedData` matching the victim certificate and answers adaptively at high volume, such as an S/MIME gateway or mail filter.

### Fix

Per RFC 3218, the content-encryption algorithm is now r…