CVE-2026-54221

MEDIUMPre-NVD 5.15.1—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.1 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 79% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
5.1
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
5.1
EG Score
5.1(medium)
EPSS
21.1%
KEV
Not listed

Published

June 18, 2026

Last Modified

June 18, 2026

Advisory Details (1)

Auto-updated Jun 18, 2026
No patch confirmed yet.
generic

Vulnerabilities in UBB.threads software | CERT Polska

https://cert.pl/en/posts/2026/06/CVE-2026-54219

Vendor Advisories for CVE-2026-54221(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 26× in last 7d / 71× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-06 21:39 UTCEG score recompute
  2. 2026-07-06 21:39 UTCGHSA enrichment
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 16:27 UTCEPSS rescore
  5. 2026-07-06 02:23 UTCEPSS rescore
  6. 2026-07-06 02:23 UTCEPSS rescore
  7. 2026-07-05 21:10 UTCEG score recompute
  8. 2026-07-05 21:10 UTCGHSA enrichment
  9. 2026-07-05 02:31 UTCEPSS rescore
  10. 2026-07-05 02:30 UTCEPSS rescore
  11. 2026-07-04 22:34 UTCEG score recompute
  12. 2026-07-04 22:33 UTCGHSA enrichment
  13. 2026-07-04 06:31 UTCEPSS rescore
  14. 2026-07-04 06:31 UTCEPSS rescore
  15. 2026-07-03 23:59 UTCEG score recompute
  16. 2026-07-03 23:59 UTCGHSA enrichment
  17. 2026-07-03 01:26 UTCEG score recompute
  18. 2026-07-03 01:26 UTCGHSA enrichment
  19. 2026-07-02 02:52 UTCEG score recompute
  20. 2026-07-02 02:52 UTCGHSA enrichment
  21. 2026-07-01 15:07 UTCEPSS rescore
  22. 2026-07-01 04:19 UTCEG score recompute
  23. 2026-07-01 04:19 UTCGHSA enrichment
  24. 2026-06-30 23:22 UTCEPSS rescore
  25. 2026-06-30 05:43 UTCEG score recompute
Show 46 more
  1. 2026-06-30 05:43 UTCGHSA enrichment
  2. 2026-06-29 14:06 UTCEPSS rescore
  3. 2026-06-29 14:06 UTCEPSS rescore
  4. 2026-06-29 07:10 UTCEG score recompute
  5. 2026-06-29 07:10 UTCGHSA enrichment
  6. 2026-06-28 14:07 UTCEPSS rescore
  7. 2026-06-28 08:34 UTCEG score recompute
  8. 2026-06-28 08:34 UTCGHSA enrichment
  9. 2026-06-28 04:56 UTCEPSS rescore
  10. 2026-06-28 04:56 UTCEPSS rescore
  11. 2026-06-27 10:00 UTCEG score recompute
  12. 2026-06-27 10:00 UTCGHSA enrichment
  13. 2026-06-27 03:08 UTCEPSS rescore
  14. 2026-06-26 11:26 UTCEG score recompute
  15. 2026-06-26 11:26 UTCGHSA enrichment
  16. 2026-06-25 13:49 UTCEPSS rescore
  17. 2026-06-25 09:25 UTCEG score recompute
  18. 2026-06-25 09:25 UTCGHSA enrichment
  19. 2026-06-24 14:05 UTCEPSS rescore
  20. 2026-06-24 10:52 UTCEG score recompute
  21. 2026-06-24 10:52 UTCGHSA enrichment
  22. 2026-06-23 21:33 UTCEPSS rescore
  23. 2026-06-23 21:33 UTCEPSS rescore
  24. 2026-06-23 12:19 UTCEG score recompute
  25. 2026-06-23 12:19 UTCGHSA enrichment
  26. 2026-06-22 14:25 UTCEPSS rescore
  27. 2026-06-22 14:25 UTCEPSS rescore
  28. 2026-06-22 13:42 UTCEG score recompute
  29. 2026-06-22 13:42 UTCGHSA enrichment
  30. 2026-06-21 15:08 UTCEG score recompute
  31. 2026-06-21 15:08 UTCGHSA enrichment
  32. 2026-06-21 14:56 UTCEPSS rescore
  33. 2026-06-21 14:56 UTCEPSS rescore
  34. 2026-06-21 01:59 UTCEPSS rescore
  35. 2026-06-21 01:59 UTCEPSS rescore
  36. 2026-06-20 16:33 UTCEG score recompute
  37. 2026-06-20 16:33 UTCGHSA enrichment
  38. 2026-06-19 19:26 UTCEPSS rescore
  39. 2026-06-19 19:26 UTCEPSS rescore
  40. 2026-06-19 17:55 UTCEG score recompute
  41. 2026-06-19 17:55 UTCGHSA enrichment
  42. 2026-06-18 19:22 UTCEG score recompute▲ 5.10
  43. 2026-06-18 19:21 UTCGHSA enrichment
  44. 2026-06-18 19:21 UTCNVD updateCVSS v3 → 5.1 · CVSS v4 → 5.1
  45. 2026-06-18 15:46 UTCEG score recompute
  46. 2026-06-18 15:45 UTCGHSA enrichment

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-54221?
CVE-2026-54221 is a medium vulnerability published on June 18, 2026. 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,…
When was CVE-2026-54221 disclosed?
CVE-2026-54221 was first published in the National Vulnerability Database on June 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-54221 actively exploited?
CVE-2026-54221 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 21.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-54221?
CVE-2026-54221 has a CVSS v3 base score of 5.1 (NVD).
How do I remediate CVE-2026-54221?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54221, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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