CVE-2026-59638 (GCVE-0-2026-59638)
Vulnerability from cvelistv5 – Published: 2026-08-03 00:57 – Updated: 2026-08-03 13:23
VLAI
EPSS
VEX
Title
JSSE hostname verifier CN-fallback enabled by default despite documented opt-in
Summary
In Bouncy Castle for Java before 1.85, JSSE hostname verifier CN-fallback enabled by default despite documented opt-in. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bctls-fips 1.0.24 (1.0.X series), 2.0.24 (2.0.X series) and 2.1.24 (2.1.X series).
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-03 13:22 UTC
CWE
- CWE-297 - Improper Validation of Certificate with Host Mismatch
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/bcgit/bc-java/wiki/CVE%E2%80%9… | vendor-advisory |
| https://github.com/bcgit/bc-java/commit/799bd1532… | patch |
| https://github.com/bcgit/bc-java/commit/5ac55351c… | patch |
Impacted products
3 products
| Vendor | Product | Version | |
|---|---|---|---|
| Legion of the Bouncy Castle Inc. | BC-JAVA |
Affected:
1.61 , < 1.85
(maven)
|
|
| Legion of the Bouncy Castle Inc. | BC-LTS-JAVA |
Affected:
2.73.0 , < 2.73.12
(maven)
|
|
| Legion of the Bouncy Castle Inc. | BC-FJA |
Affected:
1.0.7 , < 1.0.24
(maven)
Affected: 2.0.0 , < 2.0.24 (maven) Affected: 2.1.0 , < 2.1.24 (maven) |
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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