CVE-2026-13400 (GCVE-0-2026-13400)
Vulnerability from cvelistv5 – Published: 2026-07-27 06:00 – Updated: 2026-07-27 13:53
VLAI
EPSS
VEX
Title
Simply Schedule Appointments < 1.6.12.4 - Unauthenticated Stored XSS via Booking Customer Information
Summary
Simply Schedule Appointments is vulnerable to unauthenticated Stored Cross-Site Scripting in all versions up to and including 1.6.12.2. The root cause is a sanitization-ordering defect: the rendered notification content is decoded back into live HTML after it has already passed through the Simply Schedule Appointments WordPress plugin before 1.6.12.4's wp_kses_post() filter, so a double-encoded payload survives intake and is reintroduced as an executable element at render time.
Severity
6.1 (Medium)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-27 13:53 UTC
CWE
- CWE-79 Cross-Site Scripting (XSS)
- CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://wpscan.com/vulnerability/501b2929-3216-45… | exploitvdb-entrytechnical-description |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Unknown | Simply Schedule Appointments |
Affected:
0 , < 1.6.12.4
(semver)
|
guessed |
{
"containers": {
"adp": [
{
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.1,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"version": "3.1"
}
},
{
"other": {
"content": {
"id": "CVE-2026-13400",
"options": [
{
"Exploitation": "poc"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-07-27T13:53:08.821347Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-79",
"description": "CWE-79 Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-07-27T13:53:58.533Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Simply Schedule Appointments",
"vendor": "Unknown",
"versions": [
{
"lessThan": "1.6.12.4",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Revanth Hari Narayana Matte"
},
{
"lang": "en",
"type": "coordinator",
"value": "WPScan"
}
],
"descriptions": [
{
"lang": "en",
"value": "Simply Schedule Appointments is vulnerable to unauthenticated Stored Cross-Site Scripting in all versions up to and including 1.6.12.2. The root cause is a sanitization-ordering defect: the rendered notification content is decoded back into live HTML after it has already passed through the Simply Schedule Appointments WordPress plugin before 1.6.12.4\u0027s wp_kses_post() filter, so a double-encoded payload survives intake and is reintroduced as an executable element at render time."
}
],
"problemTypes": [
{
"descriptions": [
{
"description": "CWE-79 Cross-Site Scripting (XSS)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-07-27T06:00:03.496Z",
"orgId": "1bfdd5d7-9bf6-4a53-96ea-42e2716d7a81",
"shortName": "WPScan"
},
"references": [
{
"tags": [
"exploit",
"vdb-entry",
"technical-description"
],
"url": "https://wpscan.com/vulnerability/501b2929-3216-4587-8124-088fd51becf1/"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "Simply Schedule Appointments \u003c 1.6.12.4 - Unauthenticated Stored XSS via Booking Customer Information",
"x_generator": {
"engine": "WPScan CVE Generator"
}
}
},
"cveMetadata": {
"assignerOrgId": "1bfdd5d7-9bf6-4a53-96ea-42e2716d7a81",
"assignerShortName": "WPScan",
"cveId": "CVE-2026-13400",
"datePublished": "2026-07-27T06:00:03.496Z",
"dateReserved": "2026-06-26T08:35:42.471Z",
"dateUpdated": "2026-07-27T13:53:58.533Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-13400",
"date": "2026-11-04",
"epss": "0.00253",
"percentile": "0.16907"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Simply Schedule Appointments",
"vendor": "Unknown",
"versions": [
{
"lessThan": "1.6.12.4",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"source": "contact@wpscan.com"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Simply Schedule Appointments is vulnerable to unauthenticated Stored Cross-Site Scripting in all versions up to and including 1.6.12.2. The root cause is a sanitization-ordering defect: the rendered notification content is decoded back into live HTML after it has already passed through the Simply Schedule Appointments WordPress plugin before 1.6.12.4\u0027s wp_kses_post() filter, so a double-encoded payload survives intake and is reintroduced as an executable element at render time."
}
],
"id": "CVE-2026-13400",
"lastModified": "2026-07-27T20:33:01.673",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.1,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 2.7,
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-13400",
"options": [
{
"exploitation": "poc"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-07-27T13:53:08.821347Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-07-27T07:16:25.023",
"references": [
{
"source": "contact@wpscan.com",
"url": "https://wpscan.com/vulnerability/501b2929-3216-4587-8124-088fd51becf1/"
}
],
"sourceIdentifier": "contact@wpscan.com",
"vulnStatus": "Deferred",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-79"
}
],
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
]
}
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 6.1,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
"version": "3.1"
}
},
{
"other": {
"content": {
"id": "CVE-2026-13400",
"options": [
{
"Exploitation": "poc"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-07-27T13:53:08.821347Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-79",
"description": "CWE-79 Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-07-27T13:53:54.357Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Simply Schedule Appointments",
"vendor": "Unknown",
"versions": [
{
"lessThan": "1.6.12.4",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Revanth Hari Narayana Matte"
},
{
"lang": "en",
"type": "coordinator",
"value": "WPScan"
}
],
"descriptions": [
{
"lang": "en",
"value": "Simply Schedule Appointments is vulnerable to unauthenticated Stored Cross-Site Scripting in all versions up to and including 1.6.12.2. The root cause is a sanitization-ordering defect: the rendered notification content is decoded back into live HTML after it has already passed through the Simply Schedule Appointments WordPress plugin before 1.6.12.4\u0027s wp_kses_post() filter, so a double-encoded payload survives intake and is reintroduced as an executable element at render time."
}
],
"problemTypes": [
{
"descriptions": [
{
"description": "CWE-79 Cross-Site Scripting (XSS)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-07-27T06:00:03.496Z",
"orgId": "1bfdd5d7-9bf6-4a53-96ea-42e2716d7a81",
"shortName": "WPScan"
},
"references": [
{
"tags": [
"exploit",
"vdb-entry",
"technical-description"
],
"url": "https://wpscan.com/vulnerability/501b2929-3216-4587-8124-088fd51becf1/"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "Simply Schedule Appointments \u003c 1.6.12.4 - Unauthenticated Stored XSS via Booking Customer Information",
"x_generator": {
"engine": "WPScan CVE Generator"
}
}
},
"cveMetadata": {
"assignerOrgId": "1bfdd5d7-9bf6-4a53-96ea-42e2716d7a81",
"assignerShortName": "WPScan",
"cveId": "CVE-2026-13400",
"datePublished": "2026-07-27T06:00:03.496Z",
"dateReserved": "2026-06-26T08:35:42.471Z",
"dateUpdated": "2026-07-27T13:53:58.533Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
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.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
Loading timeline…
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.