FKIE_CVE-2026-54888

Vulnerability from fkie_nvd - Published: 2026-06-29 20:17 - Updated: 2026-06-30 14:14
Severity
6.9 (Medium) - CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Summary
Uncontrolled Recursion vulnerability in leandrocp mdex allows denial of service via deeply nested Markdown input. mdex converts between an Elixir %MDEx.Document{} struct and Comrak's internal AST using two mutually recursive Rust functions, ex_document_to_comrak_ast and comrak_ast_to_ex_document, in the NIF source file document.rs. Neither function enforces a maximum nesting depth, so the recursion depth is bounded only by the structure of the input. An attacker who can get a Markdown document rendered (for example through MDEx.parse_document!/1 or MDEx.to_html/1) can supply a document with thousands of nested block quotes, which drives unbounded recursion across the NIF boundary and exhausts the native C stack. Because the resulting stack overflow is an uncatchable SIGSEGV raised inside a NIF, it cannot be contained by the Erlang runtime. It terminates the operating system process running the BEAM, killing every Elixir and Erlang process on the node, not just the caller that triggered the render. No authentication or special privileges are required. The vulnerable conversion code was extracted from mdex into the separate mdex_native package starting in mdex 0.12.3. This issue affects mdex from 0.3.0 before 0.12.3 and mdex_native from 0.1.0 before 0.2.3.
References
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://cna.erlef.org/cves/CVE-2026-54888.html
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/leandrocp/mdex_native/commit/947696c47bc22bea5dffc0f78c946fa6b70ce183
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/leandrocp/mdex_native/security/advisories/GHSA-3w4f-53g2-f66p
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://osv.dev/vulnerability/EEF-CVE-2026-54888
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/leandrocp/mdex_native/security/advisories/GHSA-3w4f-53g2-f66p
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "comrak_nif",
            "\u0027Elixir.MDEx\u0027",
            "\u0027Elixir.MDEx.Native\u0027"
          ],
          "packageName": "mdex",
          "packageURL": "pkg:hex/mdex",
          "product": "mdex",
          "programFiles": [
            "native/comrak_nif/src/types/document.rs",
            "lib/mdex.ex",
            "lib/mdex/native.ex"
          ],
          "programRoutines": [
            {
              "name": "comrak_nif::types::document::ex_document_to_comrak_ast"
            },
            {
              "name": "comrak_nif::types::document::comrak_ast_to_ex_document"
            },
            {
              "name": "\u0027Elixir.MDEx\u0027:parse_document!/1"
            },
            {
              "name": "\u0027Elixir.MDEx\u0027:to_html/1"
            },
            {
              "name": "\u0027Elixir.MDEx.Native\u0027:document_to_html_with_options/2"
            }
          ],
          "repo": "https://github.com/leandrocp/mdex",
          "vendor": "leandrocp",
          "versions": [
            {
              "lessThan": "0.12.3",
              "status": "affected",
              "version": "0.3.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "comrak_nif",
            "\u0027Elixir.MDEx\u0027",
            "\u0027Elixir.MDEx.Native\u0027"
          ],
          "packageName": "leandrocp/mdex",
          "packageURL": "pkg:github/leandrocp/mdex",
          "product": "mdex",
          "programFiles": [
            "native/comrak_nif/src/types/document.rs",
            "lib/mdex.ex",
            "lib/mdex/native.ex"
          ],
          "programRoutines": [
            {
              "name": "comrak_nif::types::document::ex_document_to_comrak_ast"
            },
            {
              "name": "comrak_nif::types::document::comrak_ast_to_ex_document"
            },
            {
              "name": "\u0027Elixir.MDEx\u0027:parse_document!/1"
            },
            {
              "name": "\u0027Elixir.MDEx\u0027:to_html/1"
            },
            {
              "name": "\u0027Elixir.MDEx.Native\u0027:document_to_html_with_options/2"
            }
          ],
          "repo": "https://github.com/leandrocp/mdex",
          "vendor": "leandrocp",
          "versions": [
            {
              "lessThan": "6ed94d905f97af188323f042698ae841c02293b4",
              "status": "affected",
              "version": "d0bc7d55177727c61d188ef465178ab3b81f4f2c",
              "versionType": "git"
            }
          ]
        },
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:leandrocp:mdex_native:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "mdex_native_nif",
            "\u0027Elixir.MDExNative.Native\u0027"
          ],
          "packageName": "mdex_native",
          "packageURL": "pkg:hex/mdex_native",
          "product": "mdex_native",
          "programFiles": [
            "native/mdex_native_nif/src/types/document.rs",
            "lib/mdex_native/native.ex"
          ],
          "programRoutines": [
            {
              "name": "mdex_native_nif::types::document::ex_document_to_comrak_ast"
            },
            {
              "name": "mdex_native_nif::types::document::comrak_ast_to_ex_document"
            },
            {
              "name": "\u0027Elixir.MDExNative.Native\u0027:parse_document/2"
            },
            {
              "name": "\u0027Elixir.MDExNative.Native\u0027:document_to_html_with_options/2"
            }
          ],
          "repo": "https://github.com/leandrocp/mdex_native",
          "vendor": "leandrocp",
          "versions": [
            {
              "lessThan": "0.2.3",
              "status": "affected",
              "version": "0.1.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:leandrocp:mdex_native:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "mdex_native_nif",
            "\u0027Elixir.MDExNative.Native\u0027"
          ],
          "packageName": "leandrocp/mdex_native",
          "packageURL": "pkg:github/leandrocp/mdex_native",
          "product": "mdex_native",
          "programFiles": [
            "native/mdex_native_nif/src/types/document.rs",
            "lib/mdex_native/native.ex"
          ],
          "programRoutines": [
            {
              "name": "mdex_native_nif::types::document::ex_document_to_comrak_ast"
            },
            {
              "name": "mdex_native_nif::types::document::comrak_ast_to_ex_document"
            },
            {
              "name": "\u0027Elixir.MDExNative.Native\u0027:parse_document/2"
            },
            {
              "name": "\u0027Elixir.MDExNative.Native\u0027:document_to_html_with_options/2"
            }
          ],
          "repo": "https://github.com/leandrocp/mdex_native",
          "vendor": "leandrocp",
          "versions": [
            {
              "lessThan": "947696c47bc22bea5dffc0f78c946fa6b70ce183",
              "status": "affected",
              "version": "956528c5e31746253347029e810a969ab916fd27",
              "versionType": "git"
            }
          ]
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Uncontrolled Recursion vulnerability in leandrocp mdex allows denial of service via deeply nested Markdown input.\n\nmdex converts between an Elixir %MDEx.Document{} struct and Comrak\u0027s internal AST using two mutually recursive Rust functions, ex_document_to_comrak_ast and comrak_ast_to_ex_document, in the NIF source file document.rs. Neither function enforces a maximum nesting depth, so the recursion depth is bounded only by the structure of the input. An attacker who can get a Markdown document rendered (for example through MDEx.parse_document!/1 or MDEx.to_html/1) can supply a document with thousands of nested block quotes, which drives unbounded recursion across the NIF boundary and exhausts the native C stack.\n\nBecause the resulting stack overflow is an uncatchable SIGSEGV raised inside a NIF, it cannot be contained by the Erlang runtime. It terminates the operating system process running the BEAM, killing every Elixir and Erlang process on the node, not just the caller that triggered the render. No authentication or special privileges are required.\n\nThe vulnerable conversion code was extracted from mdex into the separate mdex_native package starting in mdex 0.12.3. This issue affects mdex from 0.3.0 before 0.12.3 and mdex_native from 0.1.0 before 0.2.3."
    }
  ],
  "id": "CVE-2026-54888",
  "lastModified": "2026-06-30T14:14:35.520",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "LOCAL",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.9,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "HIGH",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-54888",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-06-29T20:47:22.348133Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-06-29T20:17:39.230",
  "references": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://cna.erlef.org/cves/CVE-2026-54888.html"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/leandrocp/mdex_native/commit/947696c47bc22bea5dffc0f78c946fa6b70ce183"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/leandrocp/mdex_native/security/advisories/GHSA-3w4f-53g2-f66p"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-54888"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/leandrocp/mdex_native/security/advisories/GHSA-3w4f-53g2-f66p"
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-674"
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary"
    }
  ]
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.