UBUNTU-CVE-2026-118694 (CVE-2026-118694)

Vulnerability from osv_ubuntu – Published: 2026-10-28 22:17 – Updated: 2026-11-05 04:42 – Source website
VLAI
Details

python-markdown2 through 2.5.5 contains a denial of service vulnerability that allows remote users to exhaust CPU by submitting Markdown with unclosed inline link destinations. Attackers can submit repeated 'a.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7 (High)
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
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-markdown2",
            "binary_version": "2.3.7-2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "python-markdown2",
        "purl": "pkg:deb/ubuntu/python-markdown2@2.3.7-2?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.3.7-2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-markdown2",
            "binary_version": "2.4.1-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "python-markdown2",
        "purl": "pkg:deb/ubuntu/python-markdown2@2.4.1-1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.3.10-1.1",
        "2.4.1-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-markdown2",
            "binary_version": "2.4.11-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "python-markdown2",
        "purl": "pkg:deb/ubuntu/python-markdown2@2.4.11-1?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.4.1-1",
        "2.4.11-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-markdown2",
            "binary_version": "2.5.4-3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.10",
        "name": "python-markdown2",
        "purl": "pkg:deb/ubuntu/python-markdown2@2.5.4-3?arch=source\u0026distro=stonking"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.5.4-3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "python3-markdown2",
            "binary_version": "2.5.4-3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "python-markdown2",
        "purl": "pkg:deb/ubuntu/python-markdown2@2.5.4-3?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.4.11-1",
        "2.5.4-2",
        "2.5.4-3"
      ]
    }
  ],
  "aliases": [],
  "details": "python-markdown2 through 2.5.5 contains a denial of service vulnerability that allows remote users to exhaust CPU by submitting Markdown with unclosed inline link destinations. Attackers can submit repeated \u0027[a](\u0027 or \u0027![a](\u0027 sequences, causing _find_balanced to rescan the remaining document for each link and consume quadratic CPU time.",
  "id": "UBUNTU-CVE-2026-118694",
  "modified": "2026-11-05T04:42:51Z",
  "published": "2026-10-28T22:17:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-118694"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-118694"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/trentm/python-markdown2"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py#L1478-L1492"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/trentm/python-markdown2/blob/2.5.5/lib/markdown2.py#L3029"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/trentm/python-markdown2/issues/750"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/trentm/python-markdown2/pull/751"
    },
    {
      "type": "REPORT",
      "url": "https://www.vulncheck.com/advisories/python-markdown2-through-2.5.5-denial-of-service-via-unclosed-inline-link-destinations"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-118694"
  ]
}



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