VulnerabilityAnalyzed

CVE-2026-12816

In Bouncy Castle for Java before 1.85, IESEngine stream-mode MAC forgery via length-dependent KDF split.

HIGH 8.7EPSS 0.18%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.18%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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 4.0: 8.7 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.18% probability · 7th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-354
Affected: bouncycastle/bc-java · bouncycastle/bouncy castle for java lts
Source: 91579145-5d7b-4cc5-b925-a0262ff19630

EPSS trend

EPSS 0.2% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

https://github.com/bcgit/bc-java/commit/6d9e4bbaee9409713ada167e5f901554cbb084acPatch
https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012816Third Party Advisory, Patch

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.