Advisory details:
gitlab / maven/org.bouncycastle/bcprov-jdk18on/CVE-2026-12816
| Advisory ID | gitlab/maven/org.bouncycastle/bcprov-jdk18on/CVE-2026-12816 |
| Aliases |
CVE-2026-12816
|
| Summary | IESEngine stream-mode MAC forgery via length-dependent KDF split Affects Bouncy Castle for Java before 1.85. When IESEngine is initialised without a block cipher, the KDF output is split into an XOR keystream followed by the MAC key, so the MAC key offset depends on message length. Because the KDF is prefix-stable, one known plaintext reveals enough keystream to expose the MAC key for any shorter message. A passive observer can then forge authenticated ciphertexts the recipient accepts, without holding either private key. |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 0.0 |
| Risk | |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| System | Score | Found at |
|---|---|---|
| cvssv3.1 | https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/org.bouncycastle/bcprov-jdk18on/CVE-2026-12816.yml |
| Reference id | Reference type | URL |
|---|---|---|
| https://github.com/bcgit/bc-java/commit/6d9e4bbaee9409713ada167e5f901554cbb084ac | ||
| https://github.com/bcgit/bc-java/wiki/CVE-2026-12816 | ||
| CVE-2026-12816 | https://nvd.nist.gov/vuln/detail/CVE-2026-12816 |
No EPSS data available for this advisory.
| Patch URL | |
|---|---|
| There are no known patches. | |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
There are no SSVC decisions available.