CVE-2026-103601
HIGHDescription
Release of unverified plaintext in the CCM (CcmBlockCipher) and DSTU 7624 CCM (KCcmBlockCipher) AEAD modes in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker to obtain decryptions of ciphertexts of their choosing via forged messages sent to an application that lets the output buffer of a failed decryption be observed, for example through buffer reuse or logging, because decryption wrote the recovered plaintext into the caller-supplied output buffer before checking the authentication tag and left it there when the check failed. Only decryption into a caller-supplied buffer is affected; methods that return a newly allocated array are not.
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:H/I:N/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 22% 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-2026-103601?
Upgrade bc-csharp to 2.7.0 or later.
Is CVE-2026-103601 being actively exploited?
Not that we know of. CVE-2026-103601 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.29% is the estimated probability that it will be exploited in the next 30 days. That is higher than 22% of all scored CVEs.
How severe is CVE-2026-103601?
CVE-2026-103601 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-2026-103601 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.
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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 2026-10-28.