High severity · published Aug 3, 2026
CVE-2026-12816
IESEngine stream-mode MAC forgery via length-dependent KDF split
7.5
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 7% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BC
BC-JAVA · Legion of the Bouncy Castle Inc.
before 1.85 · source: vendor, NVD
BC
BC-LTS-JAVA · Legion of the Bouncy Castle Inc.
2.73.0 before 2.73.12 · source: vendor
BC
Bouncy Castle For Java Lts · Bouncycastle
through 2.73.11 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-12816
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-12816
Patch
https://github.com/bcgit/bc-java/commit/6d9e4bbaee9409713ada167e5f901554cbb084ac
Third Party Advisory
https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012816
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