Reflected XSS Vulnerability in UBB.threads by UBB Central
CVE-2026-54221

5.1MEDIUM

Key Information:

Vendor

Ubb Systems

Status
Ubb.threads
Vendor
CVE Published:
18 June 2026

What is CVE-2026-54221?

UBB.threads, a popular forum software, has a vulnerability that allows attackers to execute arbitrary JavaScript code through reflected cross-site scripting. This occurs due to improper handling of user input in certain requests, which can lead to malicious scripts running in the victim's browser. Attackers can exploit this by tricking users into clicking specially crafted links. Currently, the vulnerability has been confirmed in version 7.7.5, with the possibility of affecting other versions as well.

Affected Version(s)

UBB.threads 0 <= 7.7.5

References

https://www.ubbcentral.com/
product
https://cert.pl/en/posts/2026/06/CVE-2026-54219
third-party-advisory

CVSS V4

Score:
5.1
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Kamil Szczurowski (Securitum)
Michał Wnękowicz (Securitum)
.