FKIE_CVE-2026-53427
Vulnerability from fkie_nvd - Published: 2026-06-29 19:16 - Updated: 2026-06-29 20:17
Severity
Summary
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in leandrocp MDEx allows stored or reflected cross-site scripting via attacker-controlled Markdown.
When syntax highlighting and full info-string forwarding (render: [full_info_string: true]) are enabled, the Lumis adapter copies the value of a code fence's highlight_lines_class info-string attribute, unescaped, into the class attribute of every rendered line. comrak_nif::lumis_adapter::LumisAdapter::parse_custom_attributes in native/comrak_nif/src/lumis_adapter.rs shlex-parses the info string and stores each key=value pair verbatim, highlight_lines_config pulls highlight_lines_class into the per-line class value, and write_highlighted interpolates that value directly into the class attribute of the per-line <div>. A single-quoted shell token preserves an inner double quote through shlex parsing, so a value such as '"><script>alert(1)</script>' terminates the class attribute early and the markup that follows is emitted as live HTML.
An attacker who can submit Markdown (through comments, posts, wiki pages, documentation, or any user-generated content) can inject arbitrary HTML and JavaScript that runs in the browser of every user who views the rendered output, enabling session theft, account takeover, and other client-side attacks. No authentication or special privileges are required.
The 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.
This issue affects mdex from 0.11.3 before 0.12.3, and mdex_native from 0.1.0 before 0.2.3.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"collectionURL": "https://repo.hex.pm",
"cpes": [
"cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.MDEx\u0027",
"comrak_nif"
],
"packageName": "mdex",
"packageURL": "pkg:hex/mdex",
"product": "mdex",
"programFiles": [
"native/comrak_nif/src/lumis_adapter.rs"
],
"programRoutines": [
{
"name": "comrak_nif::lumis_adapter::LumisAdapter::parse_custom_attributes"
},
{
"name": "comrak_nif::lumis_adapter::LumisAdapter::highlight_lines_config"
},
{
"name": "comrak_nif::lumis_adapter::LumisAdapter::write_highlighted"
},
{
"name": "\u0027Elixir.MDEx\u0027:to_html/2"
}
],
"repo": "https://github.com/leandrocp/mdex",
"vendor": "leandrocp",
"versions": [
{
"lessThan": "0.12.3",
"status": "affected",
"version": "0.11.3",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.MDEx\u0027",
"comrak_nif"
],
"packageName": "leandrocp/mdex",
"packageURL": "pkg:github/leandrocp/mdex",
"product": "mdex",
"programFiles": [
"native/comrak_nif/src/lumis_adapter.rs"
],
"programRoutines": [
{
"name": "comrak_nif::lumis_adapter::LumisAdapter::parse_custom_attributes"
},
{
"name": "comrak_nif::lumis_adapter::LumisAdapter::highlight_lines_config"
},
{
"name": "comrak_nif::lumis_adapter::LumisAdapter::write_highlighted"
},
{
"name": "\u0027Elixir.MDEx\u0027:to_html/2"
}
],
"repo": "https://github.com/leandrocp/mdex",
"vendor": "leandrocp",
"versions": [
{
"lessThan": "6ed94d905f97af188323f042698ae841c02293b4",
"status": "affected",
"version": "0d7ffc84ea742e1daf666426814e5bb6d0499433",
"versionType": "git"
}
]
},
{
"collectionURL": "https://repo.hex.pm",
"cpes": [
"cpe:2.3:a:leandrocp:mdex_native:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.MDExNative.Comrak\u0027",
"mdex_native_nif"
],
"packageName": "mdex_native",
"packageURL": "pkg:hex/mdex_native",
"product": "mdex_native",
"programFiles": [
"native/mdex_native_nif/src/lumis_adapter.rs"
],
"programRoutines": [
{
"name": "mdex_native_nif::lumis_adapter::LumisAdapter::parse_custom_attributes"
},
{
"name": "mdex_native_nif::lumis_adapter::LumisAdapter::highlight_lines_config"
},
{
"name": "mdex_native_nif::lumis_adapter::LumisAdapter::write_highlighted"
},
{
"name": "\u0027Elixir.MDExNative.Native\u0027:document_to_html_with_options/2"
},
{
"name": "\u0027Elixir.MDExNative.Comrak\u0027:document_to_html/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": [
"\u0027Elixir.MDExNative.Comrak\u0027",
"mdex_native_nif"
],
"packageName": "leandrocp/mdex_native",
"packageURL": "pkg:github/leandrocp/mdex_native",
"product": "mdex_native",
"programFiles": [
"native/mdex_native_nif/src/lumis_adapter.rs"
],
"programRoutines": [
{
"name": "mdex_native_nif::lumis_adapter::LumisAdapter::parse_custom_attributes"
},
{
"name": "mdex_native_nif::lumis_adapter::LumisAdapter::highlight_lines_config"
},
{
"name": "mdex_native_nif::lumis_adapter::LumisAdapter::write_highlighted"
},
{
"name": "\u0027Elixir.MDExNative.Native\u0027:document_to_html_with_options/2"
},
{
"name": "\u0027Elixir.MDExNative.Comrak\u0027:document_to_html/2"
}
],
"repo": "https://github.com/leandrocp/mdex_native",
"vendor": "leandrocp",
"versions": [
{
"lessThan": "798a363b4339f6f7162ec8437c4c9f9b5ae6fbf3",
"status": "affected",
"version": "956528c5e31746253347029e810a969ab916fd27",
"versionType": "git"
}
]
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027) vulnerability in leandrocp MDEx allows stored or reflected cross-site scripting via attacker-controlled Markdown.\n\nWhen syntax highlighting and full info-string forwarding (render: [full_info_string: true]) are enabled, the Lumis adapter copies the value of a code fence\u0027s highlight_lines_class info-string attribute, unescaped, into the class attribute of every rendered line. comrak_nif::lumis_adapter::LumisAdapter::parse_custom_attributes in native/comrak_nif/src/lumis_adapter.rs shlex-parses the info string and stores each key=value pair verbatim, highlight_lines_config pulls highlight_lines_class into the per-line class value, and write_highlighted interpolates that value directly into the class attribute of the per-line \u003cdiv\u003e. A single-quoted shell token preserves an inner double quote through shlex parsing, so a value such as \u0027\"\u003e\u003cscript\u003ealert(1)\u003c/script\u003e\u0027 terminates the class attribute early and the markup that follows is emitted as live HTML.\n\nAn attacker who can submit Markdown (through comments, posts, wiki pages, documentation, or any user-generated content) can inject arbitrary HTML and JavaScript that runs in the browser of every user who views the rendered output, enabling session theft, account takeover, and other client-side attacks. No authentication or special privileges are required.\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 0.11.3 before 0.12.3, and mdex_native from 0.1.0 before 0.2.3."
}
],
"id": "CVE-2026-53427",
"lastModified": "2026-06-29T20:17:38.650",
"metrics": {
"cvssMetricV40": [
{
"cvssData": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"availabilityRequirement": "NOT_DEFINED",
"baseScore": 2.3,
"baseSeverity": "LOW",
"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": "LOW",
"subIntegrityImpact": "LOW",
"userInteraction": "PASSIVE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/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": "NONE",
"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-2026-53427",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-06-29T19:18:13.166991Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-06-29T19:16:41.597",
"references": [
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://cna.erlef.org/cves/CVE-2026-53427.html"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/leandrocp/mdex_native/commit/798a363b4339f6f7162ec8437c4c9f9b5ae6fbf3"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://github.com/leandrocp/mdex_native/security/advisories/GHSA-v664-pmxr-mxxx"
},
{
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-53427"
}
],
"sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"vulnStatus": "Deferred",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-79"
}
],
"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"type": "Secondary"
}
]
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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.
Loading…
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
Loading…