Cross-site Scripting (XSS) - Reflected in gnuboard/gnuboard5

Valid

Reported on

Dec 8th 2021


Description

The reflected XSS vulnerability occurs to a flaw in the clean_xss_tags() function called in memo.php of Gnuboard 5. This clean_xss_tags() is a Sanitizer that removes XSS-vulnerable tags and attributes. However, it can bypass Sanitizer by using a newline character. (%0A, %0D, ETC)

Proof of Concept

1. Open the https://sir.kr/bbs/memo.php?kind=%0D%3C/noscript%3E%3Csvg/onload=alert(document.domain)%3E&spam=1
2. you can see that occur a xss after login

Impact

Through this vulnerability, an attacker is capable to execute malicious scripts.

We are processing your report and will contact the gnuboard/gnuboard5 team within 24 hours. a year ago
Pocas modified the report
a year ago
We have contacted a member of the gnuboard/gnuboard5 team and are waiting to hear back a year ago
Pocas modified the report
a year ago
We have sent a follow up to the gnuboard/gnuboard5 team. We will try again in 7 days. a year ago
gnuboard validated this vulnerability a year ago
Pocas has been awarded the disclosure bounty
The fix bounty is now up for grabs
gnuboard marked this as fixed in 5.4.20 with commit 2e8161 a year ago
The fix bounty has been dropped
This vulnerability will not receive a CVE
Jamie Slome
a year ago

Admin


Just for reference, the researcher requested a CVE, and has been confirmed by the maintainer here.

Jamie Slome
a year ago

Admin


CVE published! 🎉

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