CVE-2026-16001
HIGHDescription
Exposure of the message authentication key through the encryption keystream in the stream mode of IesEngine (an IesEngine constructed without a block cipher) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker who has observed one encrypted message with known plaintext to forge shorter messages of their choosing that the recipient accepts as authentic, via a crafted ciphertext and MAC tag, because the MAC key was taken from the key derivation output directly after a keystream as long as the message, while the derivation input depends only on the static key pair and fixed parameters. The keystream revealed by that one message therefore contains the MAC key for every sufficiently shorter message.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 4% of all known CVEs.
References
Related Vulnerabilities
Other CWE-354 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2023-48795 | Medium | 5.9 | 94% | - | Fix |
| CVE-2019-1166 | Medium | 5.9 | 68% | - | - |
| CVE-2024-3596 | Critical | 9.0 | 15% | - | Fix |
| CVE-2020-26141 | Medium | 6.5 | 3.1% | - | Fix |
| CVE-2020-25862 | High | 7.5 | 2.4% | - | Fix |
| CVE-2023-38802 | High | 7.5 | 1.8% | - | Fix |
Common questions
How do I fix CVE-2026-16001?
Upgrade bc-csharp to 2.7.0 or later.
Is CVE-2026-16001 being actively exploited?
Not that we know of. CVE-2026-16001 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.15% is the estimated probability that it will be exploited in the next 30 days. That is higher than 4% of all scored CVEs.
How severe is CVE-2026-16001?
CVE-2026-16001 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-16001 affect?
Published advisories record a fix for bc-csharp (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-16001
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-27.