Improper Validation of Integrity Check Value Affecting org.bouncycastle:bcprov-debug-jdk18on package, versions [,1.85)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published5 Aug 2026
- disclosed3 Aug 2026
- creditUnknown
Introduced: 3 Aug 2026
NewCVE-2026-12816 (opens in a new tab)How to fix?
Upgrade org.bouncycastle:bcprov-debug-jdk18on to version 1.85 or higher.
Overview
Affected versions of this package are vulnerable to Improper Validation of Integrity Check Value enabling MAC forgery, in the IESEngine class when initialized through the 4-argument init without a block cipher, where the KDF is seeded only from the ECDH shared secret and split into a message-length K1 keystream and a K2 MAC key, so the MAC key's position depends on the message length. An attacker can forge arbitrary authenticated ciphertexts from a single known plaintext-ciphertext pair, since K1 is an XOR keystream that reveals the prefix-stable KDF output and lets the MAC keys for shorter messages be derived. This affects only stream-mode IESEngine initialized with no block cipher where the ephemeral value V is empty, and requires the attacker to hold one known plaintext-ciphertext pair.