CVE-2026-12816

High

Description

In Bouncy Castle for Java before 1.85, IESEngine stream-mode MAC forgery via length-dependent KDF split. This issue also affects Bouncy Castle for Java LTS before 2.73.12.

SeverityHigh

CVSS7.5

Exploit probability—

ProductBouncycastle Bouncy Castle For Java Lts

PublishedAug 3, 2026

First seenAug 3, 2026

Weakness typeCWE-354CWE-354

How to fix

Update

bouncycastle bc-java1.85 or later

Patches

github.com/bcgit/bc-java/commit/6d9e4bbaee9409713ada167e5f901554cbb084ac

Vendor advisories

github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012816

Affected products

Product	Affected versions	Fixed in
bouncycastle bouncy_castle_for_java_lts	v ≤ 2.73.11	—
bouncycastle bc-java	v < 1.85	1.85

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