CVE-2026-59638

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Source
https://cve.org/CVERecord?id=CVE-2026-59638
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-59638.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-59638
Downstream
CGA (2)
CLEANSTART (3)
DEBIAN (1)
openSUSE (2)
SUSE (3)
UBUNTU (1)
Related
openSUSE (2)
SUSE (3)
Published
2026-08-03T00:57:31Z
Modified
2026-10-24T14:07:50Z
Severity
  • 9.3 (Critical) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/U:Amber CVSS Calculator
Summary
JSSE hostname verifier CN-fallback enabled by default despite documented opt-in
Details

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).

Database specific 
{
    "cna_assigner": "bcorg",
    "cwe_ids": [
        "CWE-297"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59638.json",
    "unresolved_ranges": [
        {
            "extracted_events": [
                {
                    "range": [
                        {
                            "introduced": "1.0.7"
                        },
                        {
                            "fixed": "1.0.24"
                        },
                        {
                            "introduced": "2.0.0"
                        },
                        {
                            "fixed": "2.0.24"
                        },
                        {
                            "introduced": "2.1.0"
                        },
                        {
                            "fixed": "2.1.24"
                        }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                }
            ]
        }
    ]
}
References

Affected packages

Git / github.com/bcgit/bc-java

Affected ranges

Type
GIT
Repo
https://github.com/bcgit/bc-java
Events
Introduced
0f1260dc7e3c42be130c45fdad5b4363170ddf32
Fixed
57fbd3c501f7a369f64eda311d6a709fc0bcae84
Fixed
799bd15320a6310a447863638aa3df64acef829b
Fixed
5ac55351cd1a8a7184d41c96a7ee87df0770240a
Database specific
Show details 
{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "1.61"
                },
                {
                    "fixed": "1.85"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StandardRange"
        },
        {
            "range": [
                {
                    "fixed": "799bd15320a6310a447863638aa3df64acef829b"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "5ac55351cd1a8a7184d41c96a7ee87df0770240a"
                }
            ],
            "source": "REFERENCES_COMMIT"
        }
    ]
}
Type
GIT
Repo
https://github.com/bcgit/bc-lts-java
Events
Introduced
468b5082f3f0971e80bf9edb7029c17b39b9ba0c
Fixed
f101b232c5d3e07ecdd504210a57e43831d6cd65
Database specific
Show details 
{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "2.73.0"
                },
                {
                    "fixed": "2.73.12"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StandardRange"
        },
        {
            "cpe": "cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts:*:*:*:*:*:*:*:*",
            "range": [
                {
                    "introduced": "0"
                },
                {
                    "last_affected": "2.73.11"
                }
            ],
            "source": "CPE_RANGE"
        }
    ]
}

Affected versions

Other
r2rv73dot0
r2rv73dot1
r2rv73dot10
r2rv73dot11
r2rv73dot3
r2rv73dot4
r2rv73dot6
r2rv73dot8
r2rv73dot9

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-59638.json"
vanir_signatures 
[
    {
        "deprecated": false,
        "digest": {
            "function_hash": "101243177317955593101504553558978546778",
            "length": 1789
        },
        "id": "CVE-2026-59638-0f976f65",
        "signature_type": "Function",
        "signature_version": "v1",
        "source": "https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b",
        "target": {
            "file": "tls/src/main/java/org/bouncycastle/jsse/provider/HostnameUtil.java",
            "function": "checkHostname"
        }
    },
    {
        "deprecated": false,
        "digest": {
            "line_hashes": [
                "96001466807666051162215343109763009601",
                "189586970452718852126709800966206076350",
                "334434604823266146796290254048024465296",
                "230984720223366777099573014615205534404"
            ],
            "threshold": 0.9
        },
        "id": "CVE-2026-59638-c6e56e73",
        "signature_type": "Line",
        "signature_version": "v1",
        "source": "https://github.com/bcgit/bc-java/commit/799bd15320a6310a447863638aa3df64acef829b",
        "target": {
            "file": "tls/src/main/java/org/bouncycastle/jsse/provider/HostnameUtil.java"
        }
    }
]
vanir_signatures_modified 
"2026-10-24T14:07:50Z"