USN-8502-1

It was discovered that GnuTLS had a timing side-channel when processing malformed ciphertexts in RSA-PSK ClientKeyExchange. A remote attacker could possibly use this issue to recover sensitive information. This issue only affected Ubuntu 18.04 LTS. (CVE-2024-0553)

Bing Shi discovered that GnuTLS incorrectly handled decoding certain DER-encoded certificates. A remote attacker could possibly use this issue to cause GnuTLS to consume resources, leading to a denial of service. This issue only affected Ubuntu 18.04 LTS. (CVE-2024-12243)

Luigino Camastra discovered that GnuTLS incorrectly handled certain PKCS11 token labels. A remote attacker could use this issue to cause GnuTLS to crash, resulting in a denial of service, or possibly execute arbitrary code. The default compiler options for affected releases should reduce the vulnerability to a denial of service. (CVE-2025-9820)

Tim Scheckenbach discovered that GnuTLS incorrectly handled malicious certificates containing a large number of name constraints and subject alternative names. A remote attacker could possibly use this issue to cause GnuTLS to consume resources, resulting in a denial of service. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2025-14831)

Oleh Konko and Joshua Rogers discovered that GnuTLS did not properly handle case-insensitive name constraints in certain cases. A remote attacker could possibly use this issue to bypass certificate validation, leading to a machine-in-the-middle attack. (CVE-2026-3833)

Joshua Rogers discovered that GnuTLS did not properly handle very short premaster secrets in certain RSA key exchange cases with PKCS#11-backed server keys. A remote attacker could possibly use this issue to obtain sensitive information. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2026-5260)

Joshua Rogers discovered that GnuTLS did not properly handle malformed DTLS handshake fragments in certain cases. A remote attacker could possibly use this issue to obtain sensitive information, or cause a denial of service. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-33845)

Haruto Kimura, Oscar Reparaz, and Zou Dikai discovered that GnuTLS did not properly validate DTLS handshake fragment lengths in certain cases. A remote attacker could possibly use this issue to cause GnuTLS to crash, resulting in a denial of service, or execute arbitrary code. (CVE-2026-33846)

Joshua Rogers discovered that GnuTLS did not properly order DTLS packets with duplicate sequence numbers in certain cases. A remote attacker could possibly use this issue to cause GnuTLS to crash, resulting in a denial of service. (CVE-2026-42009)

Joshua Rogers discovered that GnuTLS did not properly handle usernames containing NUL characters in certain RSA-PSK configurations. A remote attacker could possibly use this issue to bypass authentication and gain unintended access to services. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-42010)

References

Affected packages

Ubuntu:Pro:16.04:LTS / gnutls28

Package

Name: gnutls28
Purl: pkg:deb/ubuntu/gnutls28?arch=source&distro=esm-infra-legacy%2Fxenial

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

3.4.10-4ubuntu1.9+esm3

Affected versions

3.*

3.3.15-5ubuntu2

3.3.18-1ubuntu1

3.3.20-1ubuntu1

3.4.9-2ubuntu1

3.4.10-4ubuntu1

3.4.10-4ubuntu1.1

3.4.10-4ubuntu1.2

3.4.10-4ubuntu1.3

3.4.10-4ubuntu1.4

3.4.10-4ubuntu1.5

3.4.10-4ubuntu1.6

3.4.10-4ubuntu1.7

3.4.10-4ubuntu1.8

3.4.10-4ubuntu1.9

3.4.10-4ubuntu1.9+esm1

3.4.10-4ubuntu1.9+esm2

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "gnutls-bin",
            "binary_version": "3.4.10-4ubuntu1.9+esm3"
        },
        {
            "binary_name": "guile-gnutls",
            "binary_version": "3.4.10-4ubuntu1.9+esm3"
        },
        {
            "binary_name": "libgnutls-openssl27",
            "binary_version": "3.4.10-4ubuntu1.9+esm3"
        },
        {
            "binary_name": "libgnutls30",
            "binary_version": "3.4.10-4ubuntu1.9+esm3"
        },
        {
            "binary_name": "libgnutlsxx28",
            "binary_version": "3.4.10-4ubuntu1.9+esm3"
        }
    ],
    "availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8502-1.json"

cves_map

{
    "ecosystem": "Ubuntu:Pro:16.04:LTS",
    "cves": [
        {
            "id": "CVE-2025-9820",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
                },
                {
                    "type": "Ubuntu",
                    "score": "low"
                }
            ]
        },
        {
            "id": "CVE-2026-3833",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
                },
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-33846",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-42009",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        }
    ]
}

Ubuntu:Pro:18.04:LTS / gnutls28

Package

Name: gnutls28
Purl: pkg:deb/ubuntu/gnutls28?arch=source&distro=esm-infra%2Fbionic

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

3.5.18-1ubuntu1.6+esm3

Affected versions

3.*

3.5.8-6ubuntu3

3.5.17-1ubuntu1

3.5.17-1ubuntu3

3.5.18-1ubuntu1

3.5.18-1ubuntu1.1

3.5.18-1ubuntu1.2

3.5.18-1ubuntu1.3

3.5.18-1ubuntu1.4

3.5.18-1ubuntu1.5

3.5.18-1ubuntu1.6

3.5.18-1ubuntu1.6+esm1

3.5.18-1ubuntu1.6+esm2

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "gnutls-bin",
            "binary_version": "3.5.18-1ubuntu1.6+esm3"
        },
        {
            "binary_name": "libgnutls-dane0",
            "binary_version": "3.5.18-1ubuntu1.6+esm3"
        },
        {
            "binary_name": "libgnutls-openssl27",
            "binary_version": "3.5.18-1ubuntu1.6+esm3"
        },
        {
            "binary_name": "libgnutls30",
            "binary_version": "3.5.18-1ubuntu1.6+esm3"
        },
        {
            "binary_name": "libgnutlsxx28",
            "binary_version": "3.5.18-1ubuntu1.6+esm3"
        }
    ],
    "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8502-1.json"

cves_map

{
    "ecosystem": "Ubuntu:Pro:18.04:LTS",
    "cves": [
        {
            "id": "CVE-2024-0553",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
                },
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2024-12243",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2025-9820",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
                },
                {
                    "type": "Ubuntu",
                    "score": "low"
                }
            ]
        },
        {
            "id": "CVE-2025-14831",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-3833",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
                },
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-5260",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-33846",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-42009",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        }
    ]
}

Ubuntu:Pro:20.04:LTS / gnutls28

Package

Name: gnutls28
Purl: pkg:deb/ubuntu/gnutls28?arch=source&distro=esm-infra%2Ffocal

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

3.6.13-2ubuntu1.12+esm2

Affected versions

3.*

3.6.9-5ubuntu1

3.6.9-5ubuntu2

3.6.10-5

3.6.11.1-2

3.6.11.1-2ubuntu2

3.6.13-2ubuntu1

3.6.13-2ubuntu1.1

3.6.13-2ubuntu1.2

3.6.13-2ubuntu1.3

3.6.13-2ubuntu1.6

3.6.13-2ubuntu1.7

3.6.13-2ubuntu1.8

3.6.13-2ubuntu1.9

3.6.13-2ubuntu1.10

3.6.13-2ubuntu1.11

3.6.13-2ubuntu1.12

3.6.13-2ubuntu1.12+esm1

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "gnutls-bin",
            "binary_version": "3.6.13-2ubuntu1.12+esm2"
        },
        {
            "binary_name": "guile-gnutls",
            "binary_version": "3.6.13-2ubuntu1.12+esm2"
        },
        {
            "binary_name": "libgnutls-dane0",
            "binary_version": "3.6.13-2ubuntu1.12+esm2"
        },
        {
            "binary_name": "libgnutls-openssl27",
            "binary_version": "3.6.13-2ubuntu1.12+esm2"
        },
        {
            "binary_name": "libgnutls30",
            "binary_version": "3.6.13-2ubuntu1.12+esm2"
        },
        {
            "binary_name": "libgnutlsxx28",
            "binary_version": "3.6.13-2ubuntu1.12+esm2"
        }
    ],
    "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-8502-1.json"

cves_map

{
    "ecosystem": "Ubuntu:Pro:20.04:LTS",
    "cves": [
        {
            "id": "CVE-2025-9820",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
                },
                {
                    "type": "Ubuntu",
                    "score": "low"
                }
            ]
        },
        {
            "id": "CVE-2025-14831",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-3833",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
                },
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-5260",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-33845",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
                },
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-33846",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-42009",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        },
        {
            "id": "CVE-2026-42010",
            "severity": [
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N"
                },
                {
                    "type": "CVSS_V3",
                    "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
                },
                {
                    "type": "Ubuntu",
                    "score": "medium"
                }
            ]
        }
    ]
}