UBUNTU-CVE-2026-50721

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Source
https://ubuntu.com/security/CVE-2026-50721
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-50721.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-50721
Upstream
Published
2026-07-02T22:16:00Z
Modified
2026-07-11T00:15:15.283507816Z
Severity
  • 8.1 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
  • 5.9 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

Libreswan, via the function RSAauthenticatehashsignatureraw_rsa(), did not correctly verify the length of the authentication hash when the SIG payload of an IKEv1 packet was encoded using PKCS #1 RSA Encryption as per RFC 2313. A remote attacker can use a variation on the Bleichenbacher attack to forge the SIG payload when small public exponents are being used (e.g., e=3), which could lead to impersonation. Additionally, a remote attacker, by encoding a shorter than expected hash in the SIG payload, could trigger an assertion leading to denial-of-service. The daemon aborts and restarts; continued exploitation causes sustained denial of service. Remote code execution is not possible. X.509 certificate verifications of remote IKE peers are not affected.

References

Affected packages

Ubuntu:18.04:LTS
libreswan

Package

Name
libreswan
Purl
pkg:deb/ubuntu/libreswan?arch=source&distro=bionic

Affected ranges

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

Affected versions

3.*
3.20-7build1
3.21-2
3.22-1
3.22-2
3.22-3
3.22-4
3.23-1
3.23-4

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libreswan",
            "binary_version": "3.23-4"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-50721.json"
Ubuntu:20.04:LTS
libreswan

Package

Name
libreswan
Purl
pkg:deb/ubuntu/libreswan?arch=source&distro=focal

Affected ranges

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

Affected versions

3.*
3.29-2
3.29-2build1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libreswan",
            "binary_version": "3.29-2build1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-50721.json"
Ubuntu:22.04:LTS
libreswan

Package

Name
libreswan
Purl
pkg:deb/ubuntu/libreswan?arch=source&distro=jammy

Affected ranges

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

Affected versions

3.*
3.32-3ubuntu3

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libreswan",
            "binary_version": "3.32-3ubuntu3"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-50721.json"
Ubuntu:24.04:LTS
libreswan

Package

Name
libreswan
Purl
pkg:deb/ubuntu/libreswan?arch=source&distro=noble

Affected ranges

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

Affected versions

4.*
4.11-1ubuntu1
4.12-1ubuntu1
4.14-1ubuntu1
4.14-1ubuntu2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libreswan",
            "binary_version": "4.14-1ubuntu2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-50721.json"
Ubuntu:25.10
libreswan

Package

Name
libreswan
Purl
pkg:deb/ubuntu/libreswan?arch=source&distro=questing

Affected ranges

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

Affected versions

4.*
4.14-1ubuntu2
5.*
5.2-2.2ubuntu1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libreswan",
            "binary_version": "5.2-2.2ubuntu1"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-50721.json"
Ubuntu:26.04:LTS
libreswan

Package

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

Affected ranges

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

Affected versions

5.*
5.2-2.2ubuntu1
5.2-2.2ubuntu2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_name": "libreswan",
            "binary_version": "5.2-2.2ubuntu2"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-50721.json"