FKIE_CVE-2026-27166
Vulnerability from fkie_nvd - Published: 2026-03-19 21:17 - Updated: 2026-06-17 10:26
Severity
4.1 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
5.4 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
5.4 (Medium) - CVSS:3.1/
Summary
Discourse is an open source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1 and 2026.1.2, insufficient cleanup in the default Codepen allowed iframes value allows an attacker to trick a user into changing the URL of the main page. This issue has been fixed in versions 2026.3.0-latest.1, 2026.2.1 and 2026.1.2. To workaround this issue, remove Codepen from the list of allowed iframes.
References
{
"affected": [
{
"affectedData": [
{
"product": "discourse",
"vendor": "discourse",
"versions": [
{
"status": "affected",
"version": "\u003c 2026.3.0-latest.1"
},
{
"status": "affected",
"version": "\u003e= 2026.2.0-latest, \u003c 2026.2.1"
},
{
"status": "affected",
"version": "\u003e= 2026.1.0-latest, \u003c 2026.1.2"
}
]
}
],
"source": "security-advisories@github.com"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*",
"matchCriteriaId": "0B441F8E-6577-4447-B9B4-767A925FAD77",
"versionEndExcluding": "2026.3.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*",
"matchCriteriaId": "4BE96625-3609-410C-B41E-4A824C1A57C0",
"versionEndExcluding": "2026.1.2",
"versionStartIncluding": "2026.1.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*",
"matchCriteriaId": "FD31CF04-CF2F-4FB9-8880-9243BC7671A7",
"versionEndExcluding": "2026.2.1",
"versionStartIncluding": "2026.2.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:discourse:discourse:2026.3.0:*:*:*:latest:*:*:*",
"matchCriteriaId": "E3FE9277-4F6B-4FD0-991F-F0FB8D226E1C",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Discourse is an open source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1 and 2026.1.2, insufficient cleanup in the default Codepen allowed iframes value allows an attacker to trick a user into changing the URL of the main page. This issue has been fixed in versions 2026.3.0-latest.1, 2026.2.1 and 2026.1.2. To workaround this issue, remove Codepen from the list of allowed iframes."
},
{
"lang": "es",
"value": "Discourse es una plataforma de discusi\u00f3n de c\u00f3digo abierto. Antes de las versiones 2026.3.0-latest.1, 2026.2.1 y 2026.1.2, una limpieza insuficiente en el valor predeterminado de iframes permitidos de Codepen permite a un atacante enga\u00f1ar a un usuario para que cambie la URL de la p\u00e1gina principal. Este problema ha sido solucionado en las versiones 2026.3.0-latest.1, 2026.2.1 y 2026.1.2. Como soluci\u00f3n alternativa a este problema, elimine Codepen de la lista de iframes permitidos."
}
],
"id": "CVE-2026-27166",
"lastModified": "2026-06-17T10:26:46.800",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 4.1,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "LOW",
"privilegesRequired": "LOW",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N",
"version": "3.1"
},
"exploitabilityScore": 2.3,
"impactScore": 1.4,
"source": "security-advisories@github.com",
"type": "Secondary"
},
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 5.4,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "LOW",
"scope": "CHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N",
"version": "3.1"
},
"exploitabilityScore": 2.3,
"impactScore": 2.7,
"source": "nvd@nist.gov",
"type": "Primary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-27166",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-03-21T03:31:46.439342Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-03-19T21:17:08.740",
"references": [
{
"source": "security-advisories@github.com",
"tags": [
"Patch"
],
"url": "https://github.com/discourse/discourse/commit/c4762a4fac2f61f52f325396b11d3aeb955ea925"
},
{
"source": "security-advisories@github.com",
"tags": [
"Vendor Advisory"
],
"url": "https://github.com/discourse/discourse/security/advisories/GHSA-h653-cq78-vjj2"
}
],
"sourceIdentifier": "security-advisories@github.com",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-80"
}
],
"source": "security-advisories@github.com",
"type": "Secondary"
}
]
}
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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.
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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.
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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.
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