BC-JAVA: Inadequate Encryption Strength
CVE-2026-59651 is a high-severity inadequate encryption strength vulnerability in BC-JAVA from Legion of the Bouncy Castle, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 1.85 as the first without the flaw, so updating BC-JAVA to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.2% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update BC-JAVA to 1.85 or a later version.
- Update BC-LTS-JAVA to 2.73.12 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Legion of the Bouncy Castle | BC-JAVA | before 1.85 | 1.85 |
| Legion of the Bouncy Castle | BC-LTS-JAVA | 2.73.0 up to, but not including, 2.73.12 | 2.73.12 |
| Bouncycastle | Bouncy Castle For Java LTS | 2.73.11 and earlier | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.1 | High | CNA |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
In Bouncy Castle for Java before 1.85, BKS keystore accepts legacy version with 16-bit integrity MAC key. This issue also affects Bouncy Castle for Java LTS before 2.73.12.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Inadequate Encryption Strength
The product stores or transmits sensitive data using an encryption scheme that is theoretically sound, but is not strong enough for the level of protection required.
How developers prevent this class of flaw
- Use an encryption scheme that is currently considered to be strong by experts in the field.
More Inadequate Encryption Strength vulnerabilities (CWE-326)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Third-party and government advisories
- github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059651Third Party Advisory
Other vulnerabilities in BC-JAVA
- 8.2 High severity
- 7.1 High severity
- 8.7 High severity
- 8.7 High severity
- 8.7 High severity
- 8.2 High severity
Recent Inadequate Encryption Strength vulnerabilities
- 9.1 Critical severity
- 7.4 High severity
- 8.8 High severity
- 7.5 High severity
- 9.1 Critical severity
- 10.0 Critical severity
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