ubuntu-cve-2026-42256
Vulnerability from osv_ubuntu
Published
2026-05-09 20:16
Modified
2026-07-06 14:11
Summary
Details

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile server can perform a computational denial-of-service attack on the client process by sending a big iteration count value. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

Severity
6.0 (Medium)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
6.5 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "jruby",
            "binary_version": "9.4.8.0+ds-3ubuntu1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "jruby",
        "purl": "pkg:deb/ubuntu/jruby@9.4.8.0+ds-3ubuntu1?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "9.4.8.0+ds-2ubuntu1",
        "9.4.8.0+ds-3ubuntu1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "libruby3.3",
            "binary_version": "3.3.8-2ubuntu2.1"
          },
          {
            "binary_name": "ruby3.3",
            "binary_version": "3.3.8-2ubuntu2.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "ruby3.3",
        "purl": "pkg:deb/ubuntu/ruby3.3@3.3.8-2ubuntu2.1?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.3.7-1ubuntu2",
        "3.3.8-2ubuntu1",
        "3.3.8-2ubuntu2",
        "3.3.8-2ubuntu2.1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libruby3.3",
            "binary_version": "3.3.8-2ubuntu3.1"
          },
          {
            "binary_name": "ruby3.3",
            "binary_version": "3.3.8-2ubuntu3.1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "ruby3.3",
        "purl": "pkg:deb/ubuntu/ruby3.3@3.3.8-2ubuntu3.1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.3.8-2ubuntu3.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3.3.8-2ubuntu2",
        "3.3.8-2ubuntu3"
      ]
    }
  ],
  "aliases": [],
  "details": "Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile server can perform a computational denial-of-service attack on the client process by sending a big iteration count value. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.",
  "id": "UBUNTU-CVE-2026-42256",
  "modified": "2026-07-06T14:11:22Z",
  "published": "2026-05-09T20:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-42256"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-42256"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/ruby/net-imap/releases/tag/v0.4.24"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/ruby/net-imap/releases/tag/v0.5.14"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/ruby/net-imap/releases/tag/v0.6.4"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/ruby/net-imap/security/advisories/GHSA-87pf-fpwv-p7m7"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8478-1"
    }
  ],
  "related": [
    "USN-8478-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-42256"
  ]
}



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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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