CVE-2026-43937: YAF.NET: Pre-Handler Authorization Bypass on Admin Pages Enabling Blind SQL Execution via `/Admin/RunSql`

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-12 · updated 2026-06-17
Weakness: CWE-89

Description

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.

Affected products

YAFNET: before 4.0.5

References

https://github.com/YAFNET/YAFNET/security/advisories/GHSA-xhw7-j96h-c3g5
https://github.com/YAFNET/YAFNET/security/advisories/GHSA-xhw7-j96h-c3g5

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