Vulnerability-Lookup

CVE-2026-41159 (GCVE-0-2026-41159)

Vulnerability from cvelistv5 – Published: 2026-05-29 13:53 – Updated: 2026-07-01 19:21

Title

Mermaid: Improper sanitization of configuration leads to CSS injection

Summary

Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Prior to 10.9.6 and 11.15.0, Mermaid's default configuration allows injecting CSS that applies outside of the Mermaid diagram via the fontFamily, themeCSS, and altFontFamily configuration options. The injected CSS exploits stylis's & (scope reference) handling. :not(&) escapes the #mermaid-xxx automatic scoping, applying styles to all page elements. Global at-rules (@font-face, @keyframes, @counter-style) are also injectable as stylis hoists them to top level. This allows page defacement and DOM attribute exfiltration via CSS :has() selectors. This vulnerability is fixed in 10.9.6 and 11.15.0.

Severity

5.3 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-94 - Improper Control of Generation of Code ('Code Injection')

Assigner

GitHub_M

References

5 references

URL	Tags
https://github.com/mermaid-js/mermaid/security/ad…	x_refsource_CONFIRM
https://github.com/mermaid-js/mermaid/commit/6476…	x_refsource_MISC
https://github.com/mermaid-js/mermaid/commit/a9d9…	x_refsource_MISC
https://github.com/mermaid-js/mermaid/releases/ta…	x_refsource_MISC
https://github.com/mermaid-js/mermaid/releases/ta…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
mermaid-js	mermaid	Affected: >= 11.0.0-alpha.1, < 11.15.0 Affected: < 10.9.6

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-41159

Vulnerability from fkie_nvd - Published: 2026-05-29 15:16 - Updated: 2026-07-21 12:10

Severity

5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aa
security-advisories@github.com	https://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76
security-advisories@github.com	https://github.com/mermaid-js/mermaid/releases/tag/mermaid@11.15.0	Release Notes
security-advisories@github.com	https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6	Release Notes
security-advisories@github.com	https://github.com/mermaid-js/mermaid/security/advisories/GHSA-87f9-hvmw-gh4p	Third Party Advisory

Impacted products

	Vendor	Product	Version
	mermaid_project	mermaid	*
	mermaid_project	mermaid	*

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "mermaid",
          "vendor": "mermaid-js",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 11.0.0-alpha.1, \u003c 11.15.0"
            },
            {
              "status": "affected",
              "version": "\u003c 10.9.6"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
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              "versionEndExcluding": "10.9.6",
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              "matchCriteriaId": "1E9D25F0-A61B-4AE3-8BE6-4246FADCAEFF",
              "versionEndExcluding": "11.15.0",
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      "lang": "en",
      "value": "Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Prior to 10.9.6 and 11.15.0,  Mermaid\u0027s default configuration allows injecting CSS that applies outside of the Mermaid diagram via the fontFamily, themeCSS, and altFontFamily configuration options. The injected CSS exploits stylis\u0027s \u0026 (scope reference) handling. :not(\u0026) escapes the #mermaid-xxx automatic scoping, applying styles to all page elements. Global at-rules (@font-face, @keyframes, @counter-style) are also injectable as stylis hoists them to top level. This allows page defacement and DOM attribute exfiltration via CSS :has() selectors. This vulnerability is fixed in 10.9.6 and 11.15.0."
    },
    {
      "lang": "es",
      "value": "Mermaid es una herramienta de JavaScript que utiliza texto inspirado en Markdown para crear y modificar diagramas y gr\u00e1ficos. Antes de las versiones 10.9.6 y 11.15.0, la configuraci\u00f3n predeterminada de Mermaid permite inyectar CSS que se aplica fuera del diagrama de Mermaid a trav\u00e9s de las opciones de configuraci\u00f3n fontFamily, themeCSS y altFontFamily. El CSS inyectado explota el manejo de \u0026 (referencia de \u00e1mbito) de stylis. :not(\u0026) escapa el alcance autom\u00e1tico #mermaid-xxx, aplicando estilos a todos los elementos de la p\u00e1gina. Las reglas globales at-rules (@font-face, @keyframes, @counter-style) tambi\u00e9n son inyectables, ya que stylis las eleva al nivel superior. Esto permite la desfiguraci\u00f3n de la p\u00e1gina y la exfiltraci\u00f3n de atributos del DOM a trav\u00e9s de selectores CSS :has(). Esta vulnerabilidad se corrige en las versiones 10.9.6 y 11.15.0."
    }
  ],
  "id": "CVE-2026-41159",
  "lastModified": "2026-07-21T12:10:00.090",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 1.4,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 5.3,
          "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": "LOW",
          "subConfidentialityImpact": "LOW",
          "subIntegrityImpact": "LOW",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L/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": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-41159",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-29T15:02:42.708368Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-05-29T15:16:22.813",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aa"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/mermaid@11.15.0"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Release Notes"
      ],
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6"
    },
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://github.com/mermaid-js/mermaid/security/advisories/GHSA-87f9-hvmw-gh4p"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-94"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-87F9-HVMW-GH4P

Vulnerability from github – Published: 2026-05-11 19:37 – Updated: 2026-07-01 19:21

Summary

Mermaid: Improper sanitization of configuration leads to CSS injection

Details

Impact

Mermaid's default configuration allows injecting CSS that applies outside of the Mermaid diagram via the fontFamily, themeCSS, and altFontFamily configuration options.

Live demo: mermaid.live

Example code:

%%{init: {"fontFamily": "x;a{b} :not(&){background:green !important} c{d}"}}%%
flowchart LR
    A --> B

The injected CSS exploits stylis's & (scope reference) handling. :not(&) escapes the #mermaid-xxx automatic scoping, applying styles to all page elements. Global at-rules (@font-face, @keyframes, @counter-style) are also injectable as stylis hoists them to top level.

This allows page defacement and DOM attribute exfiltration via CSS :has() selectors.

Patches

Workarounds

If you can't upgrade mermaid, you can set the secure config value in the mermaid config to avoid allowing diagrams to modify fontFamily, themeCSS, altFontFamily, and themeVariables.

Setting "securityLevel": "sandbox" will also prevent this.

Credits

Reported by @zsxsoft on behalf of @KeenSecurityLab

Severity

5.3 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 11.14.0"
      },
      "package": {
        "ecosystem": "npm",
        "name": "mermaid"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "11.0.0-alpha.1"
            },
            {
              "fixed": "11.15.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 10.9.5"
      },
      "package": {
        "ecosystem": "npm",
        "name": "mermaid"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "10.9.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-41159"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-94"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-11T19:37:00Z",
    "nvd_published_at": "2026-05-29T15:16:22Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nMermaid\u0027s default configuration allows injecting CSS that applies outside of the Mermaid diagram via the `fontFamily`, `themeCSS`, and `altFontFamily` configuration options.\n\nLive demo: [mermaid.live](https://mermaid.live/edit#pako:eNpNjktLxDAUhf9KvFBR6JS-60QQfODKlUvJ5k6TtsEmKTHFGUP-u-mI6Nmdy3fOPR56wwVQSBIvtXSUeAaD0e4ZlZxPDChhcLxFfwiEauOuLq_9Afv30ZpVczpaITS5kGox1qF2gfSeBwYhJAnThAyz-ewntI68vG5-0z3Z7e7IA9OQwmglB-rsKlJQwircLPgNZeAmocTPAi4GXGfHgOkQYwvqN2PUbzJuGSegA84f0a0LRyeeJI4W_xChubCPcbQD2pwbgHo4Aq2aKmvbqq3zoiu7pizqFE6RybN9VFfFY1HWXRVS-Dr_zLObrt7_V_gGGXZlGg)\n\nExample code:\n\n```\n%%{init: {\"fontFamily\": \"x;a{b} :not(\u0026){background:green !important} c{d}\"}}%%\nflowchart LR\n    A --\u003e B\n```\n\nThe injected CSS exploits stylis\u0027s `\u0026` (scope reference) handling. `:not(\u0026)` escapes the `#mermaid-xxx` automatic scoping, applying styles to all page elements. Global at-rules (`@font-face`, `@keyframes`, `@counter-style`) are also injectable as stylis hoists them to top level.\n\nThis allows page defacement and DOM attribute exfiltration via CSS `:has()` selectors.\n\n### Patches\n\n- [v11.15.0](https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.15.0) (see [64769738d5b59211e1decb471ffbaca8afec51aa](https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aa))\n- [v10.9.6](https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6) (see [a9d9f0d8eb790349121508688cd338253fd80d76](https://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76))\n\n### Workarounds\n\nIf you can\u0027t upgrade mermaid, you can set the [`secure`](https://mermaid.js.org/config/schema-docs/config.html#secure) config value in the mermaid config to avoid allowing diagrams to modify `fontFamily`, `themeCSS`, `altFontFamily`, and `themeVariables`.\n\nSetting [`\"securityLevel\": \"sandbox\"`](https://mermaid.js.org/config/schema-docs/config.html#securitylevel)  will also prevent this.\n\n### Credits\n\nReported by @zsxsoft on behalf of @KeenSecurityLab",
  "id": "GHSA-87f9-hvmw-gh4p",
  "modified": "2026-07-01T19:21:33Z",
  "published": "2026-05-11T19:37:00Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/security/advisories/GHSA-87f9-hvmw-gh4p"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41159"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aa"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/mermaid-js/mermaid"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/mermaid%4011.15.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/mermaid@11.15.0"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Mermaid: Improper sanitization of configuration leads to CSS injection"
}

ubuntu-cve-2026-41159

Vulnerability from osv_ubuntu

Published

2026-05-29 15:16

Modified

2026-06-03 11:23

Summary

Details

Severity

5.3 (Medium)


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

5.3 (Medium)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-41159	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-41159	REPORT
	https://github.com/mermaid-js/mermaid/security/ad…	REPORT
	https://github.com/mermaid-js/mermaid/commit/6476…	REPORT
	https://github.com/mermaid-js/mermaid/commit/a9d9…	REPORT
	https://github.com/mermaid-js/mermaid/commit/6476…	REPORT
	https://github.com/mermaid-js/mermaid/releases/ta…	REPORT
	https://github.com/mermaid-js/mermaid/releases/ta…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "node-mermaid",
            "binary_version": "8.13.8+~cs10.4.16-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "node-mermaid",
        "purl": "pkg:deb/ubuntu/node-mermaid@8.13.8+~cs10.4.16-1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "8.7.0+ds+~cs27.17.17-3",
        "8.13.3+ds+~cs26.13.21-1",
        "8.13.3+ds+~cs26.13.21-2",
        "8.13.8+~cs10.4.16-1"
      ]
    }
  ],
  "aliases": [],
  "details": "Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Prior to 10.9.6 and 11.15.0,  Mermaid\u0027s default configuration allows injecting CSS that applies outside of the Mermaid diagram via the fontFamily, themeCSS, and altFontFamily configuration options. The injected CSS exploits stylis\u0027s \u0026 (scope reference) handling. :not(\u0026) escapes the #mermaid-xxx automatic scoping, applying styles to all page elements. Global at-rules (@font-face, @keyframes, @counter-style) are also injectable as stylis hoists them to top level. This allows page defacement and DOM attribute exfiltration via CSS :has() selectors. This vulnerability is fixed in 10.9.6 and 11.15.0.",
  "id": "UBUNTU-CVE-2026-41159",
  "modified": "2026-06-03T11:23:42Z",
  "published": "2026-05-29T15:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-41159"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-41159"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/security/advisories/GHSA-87f9-hvmw-gh4p"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aa"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aahttps://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/mermaid@11.15.0"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-41159"
  ]
}

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.

Action not permitted

CVE-2026-41159 (GCVE-0-2026-41159)

FKIE_CVE-2026-41159

GHSA-87F9-HVMW-GH4P

Impact

Patches

Workarounds

Credits

ubuntu-cve-2026-41159

Vulnerability from osv_ubuntu

Tags

Sightings

Nomenclature