CVEvulnerability
CVE-2026-63567
8.2 HIGH
Official page ↗
- Status
- Analyzed
- Published
- 2026-10-02
- Last modified
- 2026-10-27
- Assigner
- 91579145-5d7b-4cc5-b925-a0262ff19630
- CVSS 4.0 (91579145-5d7b-4cc5-b925-a0262ff19630)
- 8.2 HIGH — CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- CVSS 3.1 ([email protected])
- 7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Weaknesses
- CWE-203
Description
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.
Affected configurations
• bouncycastle bc-csharp (< 2.7.0)
Related
Weakness · CWE (1)
- CWE-203 Observable Discrepancy weakness