UBUNTU-CVE-2026-17507

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Source
https://ubuntu.com/security/CVE-2026-17507
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-17507.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-17507
Upstream
Published
2026-10-05T00:00:00Z
Modified
2026-10-05T13:04:11Z
Severity
  • 8.7 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/U:Amber CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

In Bouncy Castle for Java before 1.86, the MLS implementation (org.bouncycastle.mls) holds RFC 9420's uint32 leaf_index in a signed int, so a wire value with the top bit set decodes to a negative number. That is a legitimate encoding rather than malformed input, and it must still decode, since the MLS interop test vectors round-trip the full range. GroupKeySet.SecretTree.hasLeaf and Group.validateRemove compared the decoded value directly against the tree's leaf count, and a signed comparison treats any negative int as less than a positive bound, so an out-of-range sender passed the membership check. In the hasLeaf case the SenderData of an unprotected PrivateMessage could then drive LeafIndex.directPath through NodeIndex.parent() arithmetic that never reaches the tree root, growing the resulting node list without bound until the JVM exhausted its heap. A single small message from any current group member could therefore deny service to every other member of the group. Both comparisons now interpret the value as unsigned via Integer.toUnsignedLong, rejecting an out-of-range sender however it was encoded; well-formed leaf indices are unaffected.

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-2026-17507.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-2026-17507.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-2026-17507.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-2026-17507.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-2026-17507.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-2026-17507.json"