{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.11.0"
              },
              {
                "fixed": "0.12.3"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "711877566dced6aa7a98a0609cf6c5cbc8971644"
            },
            {
              "fixed": "2cb9eb2f6014414b40c8f1e5d5181b9692626c38"
            }
          ],
          "repo": "https://github.com/leandrocp/mdex",
          "type": "GIT"
        },
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.1.0"
              },
              {
                "fixed": "0.2.3"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "b6caf84e9dd035654ed7e8955086ab37afdaa7a0"
            },
            {
              "fixed": "798a363b4339f6f7162ec8437c4c9f9b5ae6fbf3"
            }
          ],
          "repo": "https://github.com/leandrocp/mdex_native",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-j93q-9cvj-rxfm"
  ],
  "database_specific": {
    "cna_assigner": "EEF",
    "cwe_ids": [
      "CWE-789"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53428.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "a8407611715d1ead35fbcba79c72cef1b7df387b"
          },
          {
            "fixed": "6ed94d905f97af188323f042698ae841c02293b4"
          },
          {
            "introduced": "956528c5e31746253347029e810a969ab916fd27"
          },
          {
            "fixed": "798a363b4339f6f7162ec8437c4c9f9b5ae6fbf3"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "Memory Allocation with Excessive Size Value vulnerability in leandrocp mdex allows an unauthenticated attacker to cause a denial of service through unbounded memory allocation.\n\ncomrak_nif::lumis_adapter::LumisAdapter::parse_highlight_lines in native/comrak_nif/src/lumis_adapter.rs eagerly expands a user-controlled inclusive line range from a fenced code block's highlight_lines decorator into a Vec\u003cusize\u003e, pushing one element per integer in the range with no upper bound on the range size. An attacker who can supply Markdown that an application renders with MDEx.to_html/2 (for example a comment, chat message, or wiki page) can embed a code block whose info string is rust highlight_lines=\"1-100000000\", forcing the native adapter to allocate roughly 8 bytes per line in the range.\n\nA payload that differs by only a few bytes can therefore allocate hundreds of megabytes, and a sufficiently large range (for example 1-2000000000) exhausts host memory and aborts the BEAM, denying service to every user of the rendering process. The per-line write loop additionally tests membership with a linear scan over the same vector, degrading rendering to a quadratic cost even for ranges that do not immediately exhaust memory.\n\nThe vulnerable native code originally shipped inside mdex (in native/comrak_nif/src/lumis_adapter.rs) and was later extracted into the separate mdex_native package (native/mdex_native_nif/src/lumis_adapter.rs), where it remains unpatched.\n\nThis issue affects mdex from 0.11.0 before 0.12.3, and mdex_native from 0.1.0 before 0.2.3.",
  "id": "CVE-2026-53428",
  "modified": "2026-07-15T01:48:58.330693319Z",
  "published": "2026-06-29T18:52:36.199Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-53428.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-53428"
    },
    {
      "type": "WEB",
      "url": "https://repo.hex.pm"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53428.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/leandrocp/mdex_native/security/advisories/GHSA-j93q-9cvj-rxfm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53428"
    },
    {
      "type": "FIX",
      "url": "https://github.com/leandrocp/mdex_native/commit/798a363b4339f6f7162ec8437c4c9f9b5ae6fbf3"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/leandrocp/mdex"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/leandrocp/mdex_native"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Unbounded memory allocation in highlight_lines range expansion in mdex"
}