BC-JAVA: Use of a Broken or Risky Cryptographic Algorithm
CVE-2026-5588 is a high-severity use of a broken or risky cryptographic algorithm 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 versions 1.80.2, 1.81.1, 1.84 as the first without the flaw, so updating BC-JAVA to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.81% chance of exploitation within 30 days, higher than 57% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update BC-JAVA to 1.80.2 or 1.81.1 or 1.84, whichever matches your release line, or a later version.
- Update BCPKIX-FIPS to 2.0.11 or 2.1.11, whichever matches your release line, or a later version.
- Update BCPIX-LTS to 2.73.11 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
Version data comes from the organisation that assigned the CVE; 21 further products are omitted here. 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 CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 6.3 | Medium | CNA |
| CVSS 3.1 | 7.5 | High | CNA |
Official description
Use of a Broken or Risky Cryptographic Algorithm vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA bcpkix on all (pkix modules), Legion of the Bouncy Castle Inc. BCPKIX-FIPS bcpkix on All (pkix modules), Legion of the Bouncy Castle Inc. BCPIX-LTS bcpkix on All (pkix modules). This vulnerability is associated with program files JcaContentVerifierProviderBuilder.Java, JcaContentVerfierProviderBuilder.Java. This issue affects BC-JAVA: from 1.67 before 1.80.2, from 1.81 before 1.81.1, from 1.82 before 1.84; BCPKIX-FIPS: from 2.0.6 before 2.0.11, from 2.1.7 before 2.1.11; BCPIX-LTS: from 2.73.7 before 2.73.11.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of a Broken or Risky Cryptographic Algorithm
The product uses a broken or risky cryptographic algorithm or protocol.
How developers prevent this class of flaw
- Ensure that the design allows one cryptographic algorithm to be replaced with another in the next generation or version. Where possible, use wrappers to make the interfaces uniform. This will make it easier to upgrade to stronger algorithms. With hardware, design the product at the Intellectual Property (IP) level so that one cryptographic algorithm can be replaced with another in the next generation of the hardware product.
- Carefully manage and protect cryptographic keys (see CWE-320). If the keys can be guessed or stolen, then the strength of the cryptography itself is irrelevant.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Industry-standard implementations will save development time and may be more likely to avoid errors that can occur during implementation of cryptographic algorithms. Consider the ESAPI Encryption feature.
More Use of a Broken or Risky Cryptographic Algorithm vulnerabilities (CWE-327)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
- github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%905588
- access.redhat.com/errata/RHSA-2026:11720
- access.redhat.com/errata/RHSA-2026:11721
- access.redhat.com/errata/RHSA-2026:13631
- access.redhat.com/errata/RHSA-2026:14272
- access.redhat.com/errata/RHSA-2026:14276
- access.redhat.com/errata/RHSA-2026:17668
- access.redhat.com/errata/RHSA-2026:18054
- access.redhat.com/errata/RHSA-2026:18055
- access.redhat.com/errata/RHSA-2026:18059
- access.redhat.com/errata/RHSA-2026:21772
- access.redhat.com/errata/RHSA-2026:53644
- access.redhat.com/errata/RHSA-2026:53645
- access.redhat.com/errata/RHSA-2026:53646
- access.redhat.com/errata/RHSA-2026:60239
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 Use of a Broken or Risky Cryptographic Algorithm vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.0 High severity
- 9.1 Critical severity
- 7.5 High severity
- 9.8 Critical severity
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