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CVE-2026-54221

MEDIUMCVSS 5.1/10EPSS 0.29%

Last modified

CVE-2026-54221 is a medium-severity vulnerability rated 5.1/10 on the CVSS scale. UBB.threads is vulnerable to Reflected XSS. The application improperly handles user input in certain requests, enabling attackers to execute arbitrary JavaScript in the context of a victim's browser by tricking them into clicking a crafted link.  Because vendor contact attempts were unsuccessful, the vulnerability has only been confirmed in version 7.7.5 but may also affect other versions.. EPSS estimates a 0.29% chance of exploitation in the next 30 days.

Description

UBB.threads is vulnerable to Reflected XSS. The application improperly handles user input in certain requests, enabling attackers to execute arbitrary JavaScript in the context of a victim's browser by tricking them into clicking a crafted link.  Because vendor contact attempts were unsuccessful, the vulnerability has only been confirmed in version 7.7.5 but may also affect other versions.

Metrics

CVSS 4.0
5.1/10

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability
0.29%

20.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-54221?
UBB.threads is vulnerable to Reflected XSS. The application improperly handles user input in certain requests, enabling attackers to execute arbitrary JavaScript in the context of a victim's browser by tricking them into clicking a crafted link.  Because vendor contact attempts were unsuccessful, the vulnerability has only been confirmed in version 7.7.5 but may also affect other versions.
How severe is CVE-2026-54221?
CVE-2026-54221 has a CVSS score of 5.1/10 (MEDIUM severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.
How do I fix CVE-2026-54221?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-54221?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST