CVE-2026-77186
The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'fallback' Shortcode Attribute in all versions up to, and including, 3.8.3 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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The bypass relies on hex-encoded shortcode attribute payloads (e.g. \x3cscript\x3e), which wp_kses_post cannot strip on save because they appear as literal backslash sequences rather than real HTML tags; WordPress core's shortcode_parse_atts() then calls stripcslashes() at render time, decoding the escapes into real angle brackets before they reach the unescaped sink.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
- Puntuación base: 6.4
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.36%
- Percentil entre todas las CVEs puntuadas: 27
- Fecha de la puntuación: 5/10/2026
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)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
CWE
- CWE-79
Referencias
- https://github.com/joedolson/my-calendar/commit/89bbf7314fac84cdb89e520e8b7b6d69eee8dd3c
- https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-shortcodes.php#L114
- https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-widgets.php#L272
- https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar.php#L556
- https://www.wordfence.com/threat-intel/vulnerabilities/id/62c8fb1f-6cba-43cc-8aca-70812c29a63d?source=cve
JSON original (NVD)
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{
"id": "CVE-2026-77186",
"cveTags": [],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-77186",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"version": "2.0.3",
"timestamp": "2026-09-09T13:12:19.352858Z"
}
}
],
"cvssMetricV31": [
{
"type": "Secondary",
"source": "security@wordfence.com",
"cvssData": {
"scope": "CHANGED",
"version": "3.1",
"baseScore": 6.4,
"attackVector": "NETWORK",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
"integrityImpact": "LOW",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "NONE",
"privilegesRequired": "LOW",
"confidentialityImpact": "LOW"
},
"impactScore": 2.7,
"exploitabilityScore": 3.1
}
]
},
"affected": [
{
"source": "security@wordfence.com",
"affectedData": [
{
"vendor": "joedolson",
"product": "My Calendar – Accessible Event Manager",
"versions": [
{
"status": "affected",
"version": "0",
"versionType": "semver",
"lessThanOrEqual": "3.8.3"
}
],
"defaultStatus": "unaffected"
}
]
}
],
"published": "2026-09-09T04:19:55.880",
"references": [
{
"url": "https://github.com/joedolson/my-calendar/commit/89bbf7314fac84cdb89e520e8b7b6d69eee8dd3c",
"source": "security@wordfence.com"
},
{
"url": "https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-shortcodes.php#L114",
"source": "security@wordfence.com"
},
{
"url": "https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-widgets.php#L272",
"source": "security@wordfence.com"
},
{
"url": "https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar.php#L556",
"source": "security@wordfence.com"
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{
"url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/62c8fb1f-6cba-43cc-8aca-70812c29a63d?source=cve",
"source": "security@wordfence.com"
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"vulnStatus": "Deferred",
"weaknesses": [
{
"type": "Secondary",
"source": "security@wordfence.com",
"description": [
{
"lang": "en",
"value": "CWE-79"
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],
"descriptions": [
{
"lang": "en",
"value": "The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'fallback' Shortcode Attribute in all versions up to, and including, 3.8.3 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The bypass relies on hex-encoded shortcode attribute payloads (e.g. \\x3cscript\\x3e), which wp_kses_post cannot strip on save because they appear as literal backslash sequences rather than real HTML tags; WordPress core's shortcode_parse_atts() then calls stripcslashes() at render time, decoding the escapes into real angle brackets before they reach the unescaped sink."
}
],
"lastModified": "2026-09-09T15:33:34.467",
"sourceIdentifier": "security@wordfence.com"
}