CVE-2021-29503
HedgeDoc es una plataforma para escribir y compartir markdown. HedgeDoc versiones anteriores a 1.8.2, es vulnerable a un ataque de tipo cross-site scripting usando los metadatos YAML de una nota. Un atacante con acceso de escritura a una nota puede insertar etiquetas HTML en la sección de metadatos de Open Graph de la nota, resultando en que el frontend renderiza la etiqueta script como parte de la sección "(head)".
Leer descripción completaMostrar menos
A menos que su instancia impida a unos invitados editar unas notas, esta vulnerabilidad permite que atacantes no autentificados inyectan JavaScript en unas notas que permiten la edición de los invitados. Si su instancia impide a unos invitados editar unas notas, esta vulnerabilidad permite a atacantes autentificados inyectar JavaScript en cualquier página de notas a la que tengan acceso de escritura. Esta vulnerabilidad está parcheada en versión 1.8.2. Como solución, uno puede deshabilitar una edición de invitados hasta la próxima actualización
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- Puntuación base: 6.1
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 1.04%
- Percentil entre todas las CVEs puntuadas: 63
- Fecha de la puntuación: 9/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- CWE-80
- CWE-79
Referencias
- https://github.com/hedgedoc/hedgedoc/commit/01dad5821ee28377ebe640c6c72c3e0bb0d51ea7
- https://github.com/hedgedoc/hedgedoc/releases/tag/1.8.2
- https://github.com/hedgedoc/hedgedoc/security/advisories/GHSA-gjg7-4j2h-94fq
- https://github.com/hedgedoc/hedgedoc/commit/01dad5821ee28377ebe640c6c72c3e0bb0d51ea7
- https://github.com/hedgedoc/hedgedoc/releases/tag/1.8.2
- https://github.com/hedgedoc/hedgedoc/security/advisories/GHSA-gjg7-4j2h-94fq
JSON original (NVD)
Mostrar
{
"id": "CVE-2021-29503",
"cveTags": [],
"metrics": {
"cvssMetricV2": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"cvssData": {
"version": "2.0",
"baseScore": 4.3,
"accessVector": "NETWORK",
"vectorString": "AV:N/AC:M/Au:N/C:N/I:P/A:N",
"authentication": "NONE",
"integrityImpact": "PARTIAL",
"accessComplexity": "MEDIUM",
"availabilityImpact": "NONE",
"confidentialityImpact": "NONE"
},
"acInsufInfo": false,
"impactScore": 2.9,
"baseSeverity": "MEDIUM",
"obtainAllPrivilege": false,
"exploitabilityScore": 8.6,
"obtainUserPrivilege": false,
"obtainOtherPrivilege": false,
"userInteractionRequired": true
}
],
"cvssMetricV31": [
{
"type": "Secondary",
"source": "security-advisories@github.com",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 8.1,
"attackVector": "NETWORK",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N",
"integrityImpact": "HIGH",
"userInteraction": "REQUIRED",
"attackComplexity": "LOW",
"availabilityImpact": "NONE",
"privilegesRequired": "NONE",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.2,
"exploitabilityScore": 2.8
},
{
"type": "Primary",
"source": "nvd@nist.gov",
"cvssData": {
"scope": "CHANGED",
"version": "3.1",
"baseScore": 6.1,
"attackVector": "NETWORK",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"integrityImpact": "LOW",
"userInteraction": "REQUIRED",
"attackComplexity": "LOW",
"availabilityImpact": "NONE",
"privilegesRequired": "NONE",
"confidentialityImpact": "LOW"
},
"impactScore": 2.7,
"exploitabilityScore": 2.8
}
]
},
"affected": [
{
"source": "security-advisories@github.com",
"affectedData": [
{
"vendor": "hedgedoc",
"product": "hedgedoc",
"versions": [
{
"status": "affected",
"version": "< 1.8.2"
}
]
}
]
}
],
"published": "2021-05-19T20:15:07.440",
"references": [
{
"url": "https://github.com/hedgedoc/hedgedoc/commit/01dad5821ee28377ebe640c6c72c3e0bb0d51ea7",
"tags": [
"Patch",
"Third Party Advisory"
],
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/hedgedoc/hedgedoc/releases/tag/1.8.2",
"tags": [
"Third Party Advisory"
],
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/hedgedoc/hedgedoc/security/advisories/GHSA-gjg7-4j2h-94fq",
"tags": [
"Patch",
"Third Party Advisory"
],
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/hedgedoc/hedgedoc/commit/01dad5821ee28377ebe640c6c72c3e0bb0d51ea7",
"tags": [
"Patch",
"Third Party Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://github.com/hedgedoc/hedgedoc/releases/tag/1.8.2",
"tags": [
"Third Party Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://github.com/hedgedoc/hedgedoc/security/advisories/GHSA-gjg7-4j2h-94fq",
"tags": [
"Patch",
"Third Party Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
}
],
"vulnStatus": "Modified",
"weaknesses": [
{
"type": "Secondary",
"source": "security-advisories@github.com",
"description": [
{
"lang": "en",
"value": "CWE-80"
}
]
},
{
"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "CWE-79"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "HedgeDoc is a platform to write and share markdown. HedgeDoc before version 1.8.2 is vulnerable to a cross-site scripting attack using the YAML-metadata of a note. An attacker with write access to a note can embed HTML tags in the Open Graph metadata section of the note, resulting in the frontend rendering the script tag as part of the `<head>` section. Unless your instance prevents guests from editing notes, this vulnerability allows unauthenticated attackers to inject JavaScript into notes that allow guest edits. If your instance prevents guests from editing notes, this vulnerability allows authenticated attackers to inject JavaScript into any note pages they have write-access to. This vulnerability is patched in version 1.8.2. As a workaround, one can disable guest edits until the next update."
},
{
"lang": "es",
"value": "HedgeDoc es una plataforma para escribir y compartir markdown. HedgeDoc versiones anteriores a 1.8.2, es vulnerable a un ataque de tipo cross-site scripting usando los metadatos YAML de una nota. Un atacante con acceso de escritura a una nota puede insertar etiquetas HTML en la sección de metadatos de Open Graph de la nota, resultando en que el frontend renderiza la etiqueta script como parte de la sección \"(head)\". A menos que su instancia impida a unos invitados editar unas notas, esta vulnerabilidad permite que atacantes no autentificados inyectan JavaScript en unas notas que permiten la edición de los invitados. Si su instancia impide a unos invitados editar unas notas, esta vulnerabilidad permite a atacantes autentificados inyectar JavaScript en cualquier página de notas a la que tengan acceso de escritura. Esta vulnerabilidad está parcheada en versión 1.8.2. Como solución, uno puede deshabilitar una edición de invitados hasta la próxima actualización"
}
],
"lastModified": "2026-06-17T03:47:47.250",
"configurations": [
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:a:hedgedoc:hedgedoc:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "A017245C-AAAB-4762-B7B3-A70FCB3A1C7A",
"versionEndExcluding": "1.8.2"
}
],
"operator": "OR"
}
]
}
],
"sourceIdentifier": "security-advisories@github.com"
}