UBUNTU-CVE-2026-71892

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Source
https://ubuntu.com/security/CVE-2026-71892
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-71892
Upstream
Published
2026-10-05T00:00:00Z
Modified
2026-10-05T13:04:12Z
Severity
  • 6.9 (Medium) CVSS_V4 - 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 CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

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 Java FIPS (BC-FJA) before bcpkix-fips 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).

References

Affected packages

Ubuntu:26.04:LTS
bouncycastle

Package

Name
bouncycastle
Purl
pkg:deb/ubuntu/bouncycastle?arch=source&distro=resolute

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.80-3

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"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
Ubuntu:Pro:16.04:LTS
bouncycastle

Package

Name
bouncycastle
Purl
pkg:deb/ubuntu/bouncycastle?arch=source&distro=esm-apps%2Fxenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.49+dfsg-3ubuntu1
1.51-4ubuntu1
1.51-4ubuntu1+esm1

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"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
Ubuntu:Pro:18.04:LTS
bouncycastle

Package

Name
bouncycastle
Purl
pkg:deb/ubuntu/bouncycastle?arch=source&distro=esm-apps%2Fbionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.57-1
1.58-1
1.59-1
1.59-1ubuntu0.1~esm1

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"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
Ubuntu:Pro:20.04:LTS
bouncycastle

Package

Name
bouncycastle
Purl
pkg:deb/ubuntu/bouncycastle?arch=source&distro=esm-apps%2Ffocal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.61-1
1.61-1ubuntu0.1~esm1

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"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
Ubuntu:Pro:22.04:LTS
bouncycastle

Package

Name
bouncycastle
Purl
pkg:deb/ubuntu/bouncycastle?arch=source&distro=esm-apps%2Fjammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.68-2
1.68-4
1.68-5
1.68-5ubuntu0.1~esm1

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"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"
Ubuntu:Pro:24.04:LTS
bouncycastle

Package

Name
bouncycastle
Purl
pkg:deb/ubuntu/bouncycastle?arch=source&distro=esm-apps%2Fnoble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.72-2
1.77-1
1.77-1ubuntu0.1~esm1

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"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-71892.json"