CVE-2026-63567
HIGH
8,2
Source: 91579145-5d7b-4cc5-b925-a0262ff19630
Attack Vector: network
Attack Complexity: low
Privileges Required: none
User Interaction: none
Confidentiality: N/A
Integrity: N/A
Availability: N/A
Description
AI Translation Available
Observable discrepancy in IesEngine.DecryptBlock in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker who has captured an IES or ECIES ciphertext, and who can submit modified ciphertexts for decryption under the same key pair, to recover its plaintext via a CBC padding-oracle attack, because in block-cipher mode the engine decrypts the ciphertext and removes its padding before verifying the MAC. A padding failure is therefore reported with a different error message, and without the MAC computation, compared with a MAC failure. Only applications that construct IesEngine directly with a padded block cipher, such as AES in CBC mode with PKCS#7 padding, are affected; stream-mode IES is not.
203
Observable Discrepancy
IncompleteCommon Consequences
Security Scopes Affected:
Confidentiality
Access Control
Potential Impacts:
Read Application Data
Bypass Protection Mechanism
Applicable Platforms
All platforms may be affected
https://github.com/bcgit/bc-csharp/commit/eaa42e1e8125b3e2e25e365c4194c7cd59323…
https://github.com/bcgit/bc-csharp/commit/f881400b761134160ec2a05fd27c3e5694537…
https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63567