Vulnerability-Lookup

GHSA-22G5-R2X5-97CX

Vulnerability from github – Published: 2026-07-07 00:30 – Updated: 2026-08-07 21:03

Summary

showdown allows stored cross-site scripting through table header ID injection

Details

showdown contains a stored cross-site scripting vulnerability in the parseHeaders function of src/subParsers/makehtml/tables.js that fails to properly escape table header ID attributes. Attackers can inject arbitrary HTML and script-executing SVG elements through double-quote characters in markdown table headers, achieving stored XSS when untrusted markdown is rendered with the default github flavor configuration.

Severity

6.1 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

5.3 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "showdown"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "2.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-59710"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-07T21:03:43Z",
    "nvd_published_at": "2026-07-06T22:16:50Z",
    "severity": "MODERATE"
  },
  "details": "showdown contains a stored cross-site scripting vulnerability in the parseHeaders function of src/subParsers/makehtml/tables.js that fails to properly escape table header ID attributes. Attackers can inject arbitrary HTML and script-executing SVG elements through double-quote characters in markdown table headers, achieving stored XSS when untrusted markdown is rendered with the default github flavor configuration.",
  "id": "GHSA-22g5-r2x5-97cx",
  "modified": "2026-08-07T21:03:43Z",
  "published": "2026-07-07T00:30:59Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59710"
    },
    {
      "type": "WEB",
      "url": "https://github.com/showdownjs/showdown/issues/1046"
    },
    {
      "type": "WEB",
      "url": "https://github.com/showdownjs/showdown/commit/e5cab1e9a5dcea2bb3cbf888863fa7e65ab37edf"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/showdownjs/showdown"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/showdown-stored-xss-via-unescaped-table-header-id-attribute-injection"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "showdown allows stored cross-site scripting through table header ID injection"
}

CVE-2026-59710 (GCVE-0-2026-59710)

Vulnerability from cvelistv5 – Published: 2026-07-06 21:15 – Updated: 2026-07-07 13:47

Title

showdown - Stored XSS via Unescaped Table Header ID Attribute Injection

Summary

Severity

5.3 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

6.1 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-07 12:45 UTC

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

VulnCheck

References

4 references

URL	Tags
https://github.com/showdownjs/showdown/issues/1046	issue-tracking
https://github.com/showdownjs/showdown	product
https://github.com/showdownjs/showdown/commit/e5c…	patch
https://www.vulncheck.com/advisories/showdown-sto…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
showdown	showdown	Affected: 0 , ≤ 2.1.0 (semver)

Date Public

2026-03-12 00:00

Credits

Scott Moore - VulnCheck

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-59710",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-07T12:45:18.218566Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-07T12:45:21.229Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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          {
            "tags": [
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            ],
            "url": "https://github.com/showdownjs/showdown/issues/1046"
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        ],
        "title": "CISA ADP Vulnrichment"
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    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageURL": "pkg:npm/showdown",
          "product": "showdown",
          "vendor": "showdown",
          "versions": [
            {
              "lessThanOrEqual": "2.1.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
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                  "criteria": "cpe:2.3:a:showdownjs:showdown:*:*:*:*:*:node.js:*:*",
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                }
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        }
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      "metrics": [
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          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
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            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "LOW",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
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          "scenarios": [
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              "value": "GENERAL"
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      "problemTypes": [
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          "descriptions": [
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              "cweId": "CWE-79",
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      "providerMetadata": {
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      "references": [
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          "tags": [
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          "name": "Product",
          "tags": [
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        },
        {
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            "third-party-advisory"
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          "url": "https://www.vulncheck.com/advisories/showdown-stored-xss-via-unescaped-table-header-id-attribute-injection"
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    "datePublished": "2026-07-06T21:15:45.900Z",
    "dateReserved": "2026-07-06T15:31:46.188Z",
    "dateUpdated": "2026-07-07T13:47:54.393Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

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.

Action not permitted

GHSA-22G5-R2X5-97CX

CVE-2026-59710 (GCVE-0-2026-59710)

Tags

Sightings

Nomenclature