CVE-2026-63567
highpriority · track · 30EPSS 0.005 · 40 %ileDEUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.6–8.2
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (13)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-3713Bouncy Castle: Mehrere SchwachstellenDeutsch2026-10-01csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Bouncy Castle ausnutzen, um Sicherheitsvorkehrungen zu umgehen, Daten zu manipulieren oder offenzulegen und einen Denial-of-Service-Zustand auszulösen.
sources
Which sources assert this record, and when.
references (3) nvd
External citations — patches, advisories, analysis.
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