Quick answers
- Is CVE-2026-16001 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-16001 being exploited in the wild.
- How severe is CVE-2026-16001?
- Informational severity, published 2 October 2026.
- Which products and versions are affected?
- Legion of the Bouncy Castle Inc. Bc-Csharp before 2.7.0.
- Is there a fix for CVE-2026-16001?
- Yes: fixed in 2.7.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-16001 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-16001?
- Check whether you run Legion of the Bouncy Castle Inc. Bc-Csharp at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: 2.7.0
Technical details
The vulnerability exists in IesEngine's stream mode (when constructed without a block cipher), where the MAC key is derived directly from the keystream output after message encryption, with derivation input depending only on static key material. An attacker observing a single encrypted message with known plaintext can recover the MAC key from the exposed keystream and use it to forge authentication tags on arbitrary shorter messages, exploiting the fact that the keystream for shorter messages remains within the revealed portion.
Affected products
- Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0
Timeline
- 2026-10-02: disclosed
- 2026-06-30: patched