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usn-8431-1
Vulnerability from osv_ubuntu
Published
2026-06-15 17:24
Modified
2026-06-30 15:55
Summary
ruby2.3, ruby2.5 vulnerabilities
Details

It was discovered that Ruby's Net::IMAP library did not properly verify that Transport Layer Security (TLS) encryption was started after issuing a STARTTLS command. A remote attacker could possibly use this issue to perform a machine-in-the-middle attack and silently bypass TLS encryption. (CVE-2026-42246)

It was also discovered that Ruby's Net::IMAP library did not validate string arguments passed to certain commands. A remote attacker could possibly use this issue to inject arbitrary IMAP commands. (CVE-2026-42257)

References
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "cves_map": {
          "cves": [
            {
              "id": "CVE-2026-42246",
              "severity": [
                {
                  "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
                  "type": "CVSS_V4"
                },
                {
                  "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
                }
              ]
            },
            {
              "id": "CVE-2026-42257",
              "severity": [
                {
                  "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N",
                  "type": "CVSS_V4"
                },
                {
                  "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                  "type": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
                }
              ]
            }
          ],
          "ecosystem": "Ubuntu:Pro:16.04:LTS"
        }
      },
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libruby2.3",
            "binary_version": "2.3.1-2~ubuntu16.04.16+esm14"
          },
          {
            "binary_name": "ruby2.3",
            "binary_version": "2.3.1-2~ubuntu16.04.16+esm14"
          },
          {
            "binary_name": "ruby2.3-tcltk",
            "binary_version": "2.3.1-2~ubuntu16.04.16+esm14"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "ruby2.3",
        "purl": "pkg:deb/ubuntu/ruby2.3@2.3.1-2~ubuntu16.04.16+esm14?arch=source\u0026distro=esm-infra-legacy/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.1-2~ubuntu16.04.16+esm14"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.3.0-1",
        "2.3.0-2",
        "2.3.0-4ubuntu2",
        "2.3.0-4ubuntu3",
        "2.3.0-5ubuntu1",
        "2.3.1-2~16.04",
        "2.3.1-2~16.04.2",
        "2.3.1-2~16.04.4",
        "2.3.1-2~16.04.5",
        "2.3.1-2~16.04.6",
        "2.3.1-2~16.04.7",
        "2.3.1-2~16.04.9",
        "2.3.1-2~16.04.10",
        "2.3.1-2~16.04.11",
        "2.3.1-2~16.04.12",
        "2.3.1-2~ubuntu16.04.13",
        "2.3.1-2~ubuntu16.04.14",
        "2.3.1-2~ubuntu16.04.15",
        "2.3.1-2~ubuntu16.04.16",
        "2.3.1-2~ubuntu16.04.16+esm1",
        "2.3.1-2~ubuntu16.04.16+esm2",
        "2.3.1-2~ubuntu16.04.16+esm3",
        "2.3.1-2~ubuntu16.04.16+esm4",
        "2.3.1-2~ubuntu16.04.16+esm5",
        "2.3.1-2~ubuntu16.04.16+esm6",
        "2.3.1-2~ubuntu16.04.16+esm7",
        "2.3.1-2~ubuntu16.04.16+esm8",
        "2.3.1-2~ubuntu16.04.16+esm9",
        "2.3.1-2~ubuntu16.04.16+esm10",
        "2.3.1-2~ubuntu16.04.16+esm11",
        "2.3.1-2~ubuntu16.04.16+esm12"
      ]
    },
    {
      "database_specific": {
        "cves_map": {
          "cves": [
            {
              "id": "CVE-2026-42246",
              "severity": [
                {
                  "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
                  "type": "CVSS_V4"
                },
                {
                  "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
                }
              ]
            },
            {
              "id": "CVE-2026-42257",
              "severity": [
                {
                  "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N",
                  "type": "CVSS_V4"
                },
                {
                  "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                  "type": "CVSS_V3"
                },
                {
                  "score": "medium",
                  "type": "Ubuntu"
                }
              ]
            }
          ],
          "ecosystem": "Ubuntu:Pro:18.04:LTS"
        }
      },
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libruby2.5",
            "binary_version": "2.5.1-1ubuntu1.16+esm8"
          },
          {
            "binary_name": "ruby2.5",
            "binary_version": "2.5.1-1ubuntu1.16+esm8"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "ruby2.5",
        "purl": "pkg:deb/ubuntu/ruby2.5@2.5.1-1ubuntu1.16+esm8?arch=source\u0026distro=esm-infra/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.5.1-1ubuntu1.16+esm8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.5.0~preview1-1ubuntu2",
        "2.5.0-4ubuntu1",
        "2.5.0-4ubuntu4",
        "2.5.0-5ubuntu1",
        "2.5.0-6ubuntu1",
        "2.5.1-1ubuntu1",
        "2.5.1-1ubuntu1.1",
        "2.5.1-1ubuntu1.2",
        "2.5.1-1ubuntu1.4",
        "2.5.1-1ubuntu1.5",
        "2.5.1-1ubuntu1.6",
        "2.5.1-1ubuntu1.7",
        "2.5.1-1ubuntu1.8",
        "2.5.1-1ubuntu1.9",
        "2.5.1-1ubuntu1.10",
        "2.5.1-1ubuntu1.11",
        "2.5.1-1ubuntu1.12",
        "2.5.1-1ubuntu1.13",
        "2.5.1-1ubuntu1.14",
        "2.5.1-1ubuntu1.15",
        "2.5.1-1ubuntu1.16",
        "2.5.1-1ubuntu1.16+esm1",
        "2.5.1-1ubuntu1.16+esm3",
        "2.5.1-1ubuntu1.16+esm4",
        "2.5.1-1ubuntu1.16+esm5",
        "2.5.1-1ubuntu1.16+esm6",
        "2.5.1-1ubuntu1.16+esm7"
      ]
    }
  ],
  "aliases": [],
  "details": "It was discovered that Ruby\u0027s Net::IMAP library did not properly verify\nthat Transport Layer Security (TLS) encryption was started after issuing a STARTTLS command. A remote\nattacker could possibly use this issue to perform a machine-in-the-middle attack and silently\nbypass TLS encryption. (CVE-2026-42246)\n\nIt was also discovered that Ruby\u0027s Net::IMAP library did not validate\nstring arguments passed to certain commands. A remote attacker could possibly use this issue to\ninject arbitrary IMAP commands. (CVE-2026-42257)",
  "id": "USN-8431-1",
  "modified": "2026-06-30T15:55:21Z",
  "published": "2026-06-15T17:24:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8431-1"
    },
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-42246"
    },
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-42257"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "summary": "ruby2.3, ruby2.5 vulnerabilities",
  "upstream": [
    "UBUNTU-CVE-2026-42246",
    "UBUNTU-CVE-2026-42257"
  ]
}



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