bouncycastle — security advisory
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against the id-alg-cek-hkdf-sha256 object identifier, a comparison between a byte array and an ASN1ObjectIdentifier that is false for every possible input, so the check fell through to a key-size lookup on the outer wrapper OID. That OID identifies a key-derivation construction rather than a cipher and has no registered key size, so the size comparison was skipped entirely. A key-transport EnvelopedData or AuthEnvelopedData whose transported, HKDF-derived content-encryption key did not match the key size of the advertised content-encryption algorithm was therefore accepted even with validation explicitly enabled, silently defeating the only mechanism the API offers for enforcing recovered key size. The recipient now dispatches on the content-encryption AlgorithmIdentifier's algorithm OID, so validation checks the recovered key against the inner content-encryption algorithm. Messages with a matching key size, non-HKDF messages, and recipients that do not enable validation are unaffected. This issue also affects Bouncy Castle for
- Products
- bouncycastle
- Affected versions
- 1.49+dfsg-3ubuntu1, 1.51-4ubuntu1, 1.51-4ubuntu1+esm1, 1.57-1, 1.58-1, 1.59-1, 1.59-1ubuntu0.1~esm1, 1.61-1, 1.61-1ubuntu0.1~esm1, 1.68-2, 1.68-4, 1.68-5, 1.68-5ubuntu0.1~esm1, 1.72-2, 1.77-1, 1.77-1ubuntu0.1~esm1, 1.80-3
- Fixed versions
- Not specified
- CVEs
- CVE-2026-71892
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:15 UTC · Revision 1
Source evidence
In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against the id-alg-cek-hkdf-sha256 object identifier, a comparison between a byte array and an ASN1ObjectIdentifier that is false for every possible input, so the check fell through to a key-size lookup on the outer wrapper OID. That OID identifies a key-derivation construction rather than a cipher and has no registered key size, so the size comparison was skipped entirely. A key-transport EnvelopedData or AuthEnvelopedData whose transported, HKDF-derived content-encryption key did not match the key size of the advertised content-encryption algorithm was therefore accepted even with validation explicitly enabled, silently defeating the only mechanism the API offers for enforcing recovered key size. The recipient now dispatches on the content-encryption AlgorithmIdentifier's algorithm OID, so validation checks the recovered key against the inner content-encryption algorithm. Messages with a matching key size, non-HKDF messages, and recipients that do not enable validation are unaffected. This issue also affects Bouncy Castle for
osv:UBUNTU-CVE-2026-71892
bouncycastle
Fixed versions: Not specified
bouncycastle
Fixed versions: Not specified
bouncycastle
Fixed versions: Not specified
bouncycastle
Fixed versions: Not specified
bouncycastle
Fixed versions: Not specified
bouncycastle
Fixed versions: Not specified
bouncycastle
Fixed versions: Not specified
Complete source record
{
"id": "67a087605995bc029058f214e07a3dd3f4c3351f5e68be93e83e08fade3c2a34",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-71892",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-71892",
"summary": "In Bouncy Castle for Java before 1.86, the opt-in key-size validation on CMS key-transport recipients, org.bouncycastle.cms.jcajce.JceKeyTransRecipient.setKeySizeValidation(true), never ran for a message using RFC 9709 content-encryption key derivation (id-alg-cek-hkdf-sha256). The branch that should have selected the actual content-encryption algorithm carried in the key derivation AlgorithmIdentifier's parameters compared the encrypted-key byte array against the id-alg-cek-hkdf-sha256 object identifier, a comparison between a byte array and an ASN1ObjectIdentifier that is false for every possible input, so the check fell through to a key-size lookup on the outer wrapper OID. That OID identifies a key-derivation construction rather than a cipher and has no registered key size, so the size comparison was skipped entirely. A key-transport EnvelopedData or AuthEnvelopedData whose transported, HKDF-derived content-encryption key did not match the key size of the advertised content-encryption algorithm was therefore accepted even with validation explicitly enabled, silently defeating the only mechanism the API offers for enforcing recovered key size. The recipient now dispatches on the content-encryption AlgorithmIdentifier's algorithm OID, so validation checks the recovered key against the inner content-encryption algorithm. Messages with a matching key size, non-HKDF messages, and recipients that do not enable validation are unaffected. This issue also affects Bouncy Castle for",
"evidence": "osv:UBUNTU-CVE-2026-71892",
"products": [
{
"name": {
"value": "bouncycastle",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.49+dfsg-3ubuntu1",
"evidence": "/affected/0/versions"
},
{
"value": "1.51-4ubuntu1",
"evidence": "/affected/0/versions"
},
{
"value": "1.51-4ubuntu1+esm1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "bouncycastle",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.57-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.58-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.59-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.59-1ubuntu0.1~esm1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "bouncycastle",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.61-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.61-1ubuntu0.1~esm1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "bouncycastle",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.68-2",
"evidence": "/affected/3/versions"
},
{
"value": "1.68-4",
"evidence": "/affected/3/versions"
},
{
"value": "1.68-5",
"evidence": "/affected/3/versions"
},
{
"value": "1.68-5ubuntu0.1~esm1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "bouncycastle",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.72-2",
"evidence": "/affected/4/versions"
},
{
"value": "1.77-1",
"evidence": "/affected/4/versions"
},
{
"value": "1.77-1ubuntu0.1~esm1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "bouncycastle",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.80-3",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "bouncycastle",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.80-3",
"evidence": "/affected/6/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-71892",
"aliases": [
"UBUNTU-CVE-2026-71892"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/U:Amber"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "bouncycastle",
"purl": "pkg:deb/ubuntu/bouncycastle?arch=source&distro=esm-apps%2Fxenial",
"ecosystem": "Ubuntu:Pro:16.04:LTS"
},
"versions": [
"1.49+dfsg-3ubuntu1",
"1.51-4ubuntu1",
"1.51-4ubuntu1+esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libbcmail-java",
"binary_version": "1.51-4ubuntu1+esm1"
},
{
"binary_name": "libbcpg-java",
"binary_version": "1.51-4ubuntu1+esm1"
},
{
"binary_name": "libbcpkix-java",
"binary_version": "1.51-4ubuntu1+esm1"
},
{
"binary_name": "libbcprov-java",
"binary_version": "1.51-4ubuntu1+esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "bouncycastle",
"purl": "pkg:deb/ubuntu/bouncycastle?arch=source&distro=esm-apps%2Fbionic",
"ecosystem": "Ubuntu:Pro:18.04:LTS"
},
"versions": [
"1.57-1",
"1.58-1",
"1.59-1",
"1.59-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libbcmail-java",
"binary_version": "1.59-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcpg-java",
"binary_version": "1.59-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcpkix-java",
"binary_version": "1.59-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcprov-java",
"binary_version": "1.59-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "bouncycastle",
"purl": "pkg:deb/ubuntu/bouncycastle?arch=source&distro=esm-apps%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
"versions": [
"1.61-1",
"1.61-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libbcmail-java",
"binary_version": "1.61-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcpg-java",
"binary_version": "1.61-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcpkix-java",
"binary_version": "1.61-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcprov-java",
"binary_version": "1.61-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "bouncycastle",
"purl": "pkg:deb/ubuntu/bouncycastle?arch=source&distro=esm-apps%2Fjammy",
"ecosystem": "Ubuntu:Pro:22.04:LTS"
},
"versions": [
"1.68-2",
"1.68-4",
"1.68-5",
"1.68-5ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libbcmail-java",
"binary_version": "1.68-5ubuntu0.1~esm1"
},
{
"binary_name": "libbcpg-java",
"binary_version": "1.68-5ubuntu0.1~esm1"
},
{
"binary_name": "libbcpkix-java",
"binary_version": "1.68-5ubuntu0.1~esm1"
},
{
"binary_name": "libbcprov-java",
"binary_version": "1.68-5ubuntu0.1~esm1"
},
{
"binary_name": "libbctls-java",
"binary_version": "1.68-5ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "bouncycastle",
"purl": "pkg:deb/ubuntu/bouncycastle?arch=source&distro=esm-apps%2Fnoble",
"ecosystem": "Ubuntu:Pro:24.04:LTS"
},
"versions": [
"1.72-2",
"1.77-1",
"1.77-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libbcjmail-java",
"binary_version": "1.77-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcmail-java",
"binary_version": "1.77-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcpg-java",
"binary_version": "1.77-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcpkix-java",
"binary_version": "1.77-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcprov-java",
"binary_version": "1.77-1ubuntu0.1~esm1"
},
{
"binary_name": "libbctls-java",
"binary_version": "1.77-1ubuntu0.1~esm1"
},
{
"binary_name": "libbcutil-java",
"binary_version": "1.77-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "bouncycastle",
"purl": "pkg:deb/ubuntu/bouncycastle?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"1.80-3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libbcjmail-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbcmail-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbcpg-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbcpkix-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbcprov-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbctls-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbcutil-java",
"binary_version": "1.80-3"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "bouncycastle",
"purl": "pkg:deb/ubuntu/bouncycastle?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.80-3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libbcjmail-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbcmail-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbcpg-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbcpkix-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbcprov-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbctls-java",
"binary_version": "1.80-3"
},
{
"binary_name": "libbcutil-java",
"binary_version": "1.80-3"
}
]
}
}
],
"modified": "2026-10-17T13:00:47.348333898Z",
"provider": "osv",
"upstream": [
"CVE-2026-71892"
],
"references": [
"https://ubuntu.com/security/CVE-2026-71892",
"https://www.cve.org/CVERecord?id=CVE-2026-71892",
"https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9071892",
"https://github.com/bcgit/bc-java/commit/be0a7d925c818ef2f338bcec55178b9b6336dfc3"
]
},
"related_cves": [
{
"value": "CVE-2026-71892",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 360838,
"published_at": "2026-10-03T09:17:00+00:00"
}