CVE-2026-63567
HIGH
MEDIUM
Priority: 0.04
BB Relevance:
76/100
Published: 2026-10-02
Modified: 2026-10-27
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
No Auth
No Interaction
Conf. Impact
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
None
S:
X
AT:
Present
VC:
High
VI:
None
VA:
None
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.
Weakness Classification (1)
Affected Software (1)
| Vendor | Product | Version |
|---|---|---|
| bouncycastle | bc-csharp | < 2.7.0 |
References & Advisories (3)
Patch
Vendor Advisory
Patch
Patch