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6 vulnerabilities by YAFNET
CVE-2026-43939 (GCVE-0-2026-43939)
Vulnerability from nvd – Published: 2026-05-12 13:56 – Updated: 2026-05-13 14:38
VLAI
Title
YAF.NET: Stored XSS in Forum Thread Posts/Replies Allowing Arbitrary JavaScript Execution for All Thread Viewers
Summary
YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5 and 3.2.12, the thread posting and reply feature accepts user-supplied content via a a post or reply that is stored server-side and later rendered back into the thread page without adequate HTML sanitization or contextual output encoding. This vulnerability is fixed in 4.0.5 and 3.2.12.
Severity
7.3 (High)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/YAFNET/YAFNET/security/advisor… | x_refsource_CONFIRM |
Impacted products
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CVE-2026-43938 (GCVE-0-2026-43938)
Vulnerability from nvd – Published: 2026-05-12 13:57 – Updated: 2026-05-12 15:39
VLAI
Title
YAF.NET: Unauthenticated Stored Second-Order XSS in Admin Event Log via Reflected `User-Agent` Header
Summary
YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5 and 3.2.12, the application's database logger (YAFNET.Core/Logger/DbLogger.cs) captures the incoming request's User-Agent header into a JObject, serializes it with JsonConvert, and stores the result in the EventLog.Description column whenever an event (e.g., an unhandled exception) is logged. The admin event-log page (YetAnotherForum.NET/Pages/Admin/EventLog.cshtml.cs) later deserializes that JSON in FormatStackTrace() and interpolates the UserAgent value directly into an HTML string with no encoding, and the Razor view EventLog.cshtml emits the result through @Html.Raw. This vulnerability is fixed in 4.0.5 and 3.2.12.
Severity
8.1 (High)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/YAFNET/YAFNET/security/advisor… | x_refsource_CONFIRM |
Impacted products
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}
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CVE-2026-43937 (GCVE-0-2026-43937)
Vulnerability from nvd – Published: 2026-05-12 14:00 – Updated: 2026-05-12 15:42
VLAI
Title
YAF.NET: Pre-Handler Authorization Bypass on Admin Pages Enabling Blind SQL Execution via `/Admin/RunSql`
Summary
YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5, Any admin OnPost… handler executes its side effects before the ResultFilterAttribute rewrites the response to a 302 to /Info/4. The most impactful abuse is /Admin/RunSql, whose OnPostRunQuery binds Editor from the POST body and passes it straight to IDbAccess.RunSql with no caller check, yielding arbitrary SQL execution for any low-privileged user. This vulnerability is fixed in 4.0.5.
Severity
8.8 (High)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/YAFNET/YAFNET/security/advisor… | x_refsource_CONFIRM |
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}
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"timestamp": "2026-05-12T15:42:40.301152Z",
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CVE-2026-43937 (GCVE-0-2026-43937)
Vulnerability from cvelistv5 – Published: 2026-05-12 14:00 – Updated: 2026-05-12 15:42
VLAI
Title
YAF.NET: Pre-Handler Authorization Bypass on Admin Pages Enabling Blind SQL Execution via `/Admin/RunSql`
Summary
YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5, Any admin OnPost… handler executes its side effects before the ResultFilterAttribute rewrites the response to a 302 to /Info/4. The most impactful abuse is /Admin/RunSql, whose OnPostRunQuery binds Editor from the POST body and passes it straight to IDbAccess.RunSql with no caller check, yielding arbitrary SQL execution for any low-privileged user. This vulnerability is fixed in 4.0.5.
Severity
8.8 (High)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/YAFNET/YAFNET/security/advisor… | x_refsource_CONFIRM |
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CVE-2026-43938 (GCVE-0-2026-43938)
Vulnerability from cvelistv5 – Published: 2026-05-12 13:57 – Updated: 2026-05-12 15:39
VLAI
Title
YAF.NET: Unauthenticated Stored Second-Order XSS in Admin Event Log via Reflected `User-Agent` Header
Summary
YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5 and 3.2.12, the application's database logger (YAFNET.Core/Logger/DbLogger.cs) captures the incoming request's User-Agent header into a JObject, serializes it with JsonConvert, and stores the result in the EventLog.Description column whenever an event (e.g., an unhandled exception) is logged. The admin event-log page (YetAnotherForum.NET/Pages/Admin/EventLog.cshtml.cs) later deserializes that JSON in FormatStackTrace() and interpolates the UserAgent value directly into an HTML string with no encoding, and the Razor view EventLog.cshtml emits the result through @Html.Raw. This vulnerability is fixed in 4.0.5 and 3.2.12.
Severity
8.1 (High)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/YAFNET/YAFNET/security/advisor… | x_refsource_CONFIRM |
Impacted products
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"vendor": "YAFNET",
"versions": [
{
"status": "affected",
"version": "\u003e= 4.0.0-beta.1, \u003c 4.0.5"
},
{
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"version": "\u003c 3.2.12"
}
]
}
],
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{
"lang": "en",
"value": "YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5 and 3.2.12, the application\u0027s database logger (YAFNET.Core/Logger/DbLogger.cs) captures the incoming request\u0027s User-Agent header into a JObject, serializes it with JsonConvert, and stores the result in the EventLog.Description column whenever an event (e.g., an unhandled exception) is logged. The admin event-log page (YetAnotherForum.NET/Pages/Admin/EventLog.cshtml.cs) later deserializes that JSON in FormatStackTrace() and interpolates the UserAgent value directly into an HTML string with no encoding, and the Razor view EventLog.cshtml emits the result through @Html.Raw. This vulnerability is fixed in 4.0.5 and 3.2.12."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 8.1,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N",
"version": "3.1"
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"description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
"lang": "en",
"type": "CWE"
}
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{
"descriptions": [
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"cweId": "CWE-80",
"description": "CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-116",
"description": "CWE-116: Improper Encoding or Escaping of Output",
"lang": "en",
"type": "CWE"
}
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}
],
"providerMetadata": {
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},
"references": [
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"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-33gv-fc78-qgf5"
}
],
"source": {
"advisory": "GHSA-33gv-fc78-qgf5",
"discovery": "UNKNOWN"
},
"title": "YAF.NET: Unauthenticated Stored Second-Order XSS in Admin Event Log via Reflected `User-Agent` Header"
}
},
"cveMetadata": {
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"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-43938",
"datePublished": "2026-05-12T13:57:56.951Z",
"dateReserved": "2026-05-04T16:59:09.089Z",
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CVE-2026-43939 (GCVE-0-2026-43939)
Vulnerability from cvelistv5 – Published: 2026-05-12 13:56 – Updated: 2026-05-13 14:38
VLAI
Title
YAF.NET: Stored XSS in Forum Thread Posts/Replies Allowing Arbitrary JavaScript Execution for All Thread Viewers
Summary
YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5 and 3.2.12, the thread posting and reply feature accepts user-supplied content via a a post or reply that is stored server-side and later rendered back into the thread page without adequate HTML sanitization or contextual output encoding. This vulnerability is fixed in 4.0.5 and 3.2.12.
Severity
7.3 (High)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: total
CISA Coordinator (v2.0.3)
CWE
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/YAFNET/YAFNET/security/advisor… | x_refsource_CONFIRM |
Impacted products
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-43939",
"options": [
{
"Exploitation": "poc"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-05-13T14:32:49.648146Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-05-13T14:38:25.692Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"references": [
{
"tags": [
"exploit"
],
"url": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-8rq5-wwpp-fmj2"
}
],
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "YAFNET",
"vendor": "YAFNET",
"versions": [
{
"status": "affected",
"version": "\u003e= 4.0.0-beta.1, \u003c 4.0.5"
},
{
"status": "affected",
"version": "\u003c 3.2.12"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5 and 3.2.12, the thread posting and reply feature accepts user-supplied content via a a post or reply that is stored server-side and later rendered back into the thread page without adequate HTML sanitization or contextual output encoding. This vulnerability is fixed in 4.0.5 and 3.2.12."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 7.3,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N",
"version": "3.1"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-79",
"description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-80",
"description": "CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-116",
"description": "CWE-116: Improper Encoding or Escaping of Output",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-05-12T13:56:39.586Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-8rq5-wwpp-fmj2",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-8rq5-wwpp-fmj2"
}
],
"source": {
"advisory": "GHSA-8rq5-wwpp-fmj2",
"discovery": "UNKNOWN"
},
"title": "YAF.NET: Stored XSS in Forum Thread Posts/Replies Allowing Arbitrary JavaScript Execution for All Thread Viewers"
}
},
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"datePublished": "2026-05-12T13:56:39.586Z",
"dateReserved": "2026-05-04T16:59:09.089Z",
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"state": "PUBLISHED"
},
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