CVE-2026-12816

IESEngine stream-mode MAC forgery via length-dependent KDF split

HIGH

7.5

CVSS Score

Published: August 3, 2026 at 02:53 AM UTC

Updated: September 2, 2026 at 02:52 PM UTC

3 products affected across 2 vendorsBc JavaBouncy Castle for Java LtsBC Java

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Severity

HIGH7.5

Exploit prediction

EPSS 0.2%

SSVC

No known 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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Bc Java · Bouncycastle

95%

v < 1.85

Affected range stops below 1.85, so it looks safe — our inference, not a vendor statement

Bouncy Castle for Java Lts · Bouncycastle

95%

v ≤ 2.73.11

BC Java · Legion of Bouncy Castlemaven

60%

v < 1.852.73.0 ≤ v < 2.73.122.73.0

Affected range stops below 1.85, so it looks safe — our inference, not a vendor statement

Affected range stops below 2.73.12, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (3)

Source: cverecord

https://github.com/bcgit/bc-java/wiki/CVE-2026-12816

Patch

Source: cverecord

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

Vendor AdvisoryThird Party AdvisoryPatch

Source: cverecord

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

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGH[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: HIGH
Availability: NONE

Vector?

Quick Info

StatusANALYZED

CWE

CWE-354

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