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
5.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.1Exploit: None knownExposed: 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)
EG Risk
28(Track)
EG Risk 28/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity51% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
22%
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 5× in last 7d / 48× 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.

Showing the most recent 100 of 187 total refreshes for this CVE.

  1. 2026-09-11 14:53 UTCEPSS rescore
  2. 2026-09-10 09:35 UTCEPSS rescore
  3. 2026-09-08 22:01 UTCEPSS rescore
  4. 2026-09-07 16:01 UTCEPSS rescore
  5. 2026-09-06 13:47 UTCEPSS rescore
  6. 2026-09-04 05:06 UTCEPSS rescore
  7. 2026-09-02 14:12 UTCEPSS rescore
  8. 2026-09-01 13:54 UTCEPSS rescore
  9. 2026-09-01 04:40 UTCEPSS rescore
  10. 2026-08-30 21:00 UTCEG score recompute
  11. 2026-08-30 21:00 UTCGHSA enrichment
  12. 2026-08-30 19:17 UTCEPSS rescore
  13. 2026-08-30 01:22 UTCEPSS rescore
  14. 2026-08-28 21:41 UTCEPSS rescore
  15. 2026-08-27 14:25 UTCEPSS rescore
  16. 2026-08-26 14:46 UTCEPSS rescore
  17. 2026-08-25 13:49 UTCEPSS rescore
  18. 2026-08-24 22:19 UTCEG score recompute
  19. 2026-08-24 22:19 UTCGHSA enrichment
  20. 2026-08-23 23:45 UTCGHSA enrichment
  21. 2026-08-23 01:12 UTCEG score recompute
  22. 2026-08-23 01:12 UTCGHSA enrichment
  23. 2026-08-23 00:19 UTCEPSS rescore
  24. 2026-08-21 23:49 UTCEPSS rescore
  25. 2026-08-21 06:42 UTCEG score recompute
Show 75 more
  1. 2026-08-21 06:42 UTCGHSA enrichment
  2. 2026-08-20 22:55 UTCEPSS rescore
  3. 2026-08-20 08:09 UTCEG score recompute
  4. 2026-08-20 08:09 UTCGHSA enrichment
  5. 2026-08-19 17:04 UTCEPSS rescore
  6. 2026-08-19 07:44 UTCEG score recompute
  7. 2026-08-19 07:44 UTCGHSA enrichment
  8. 2026-08-18 13:48 UTCEPSS rescore
  9. 2026-08-17 13:47 UTCEPSS rescore
  10. 2026-08-17 06:12 UTCEG score recompute
  11. 2026-08-17 06:12 UTCGHSA enrichment
  12. 2026-08-16 14:56 UTCEPSS rescore
  13. 2026-08-16 07:38 UTCEG score recompute
  14. 2026-08-16 07:38 UTCGHSA enrichment
  15. 2026-08-16 02:14 UTCEPSS rescore
  16. 2026-08-15 09:06 UTCEG score recompute
  17. 2026-08-15 09:06 UTCGHSA enrichment
  18. 2026-08-15 01:30 UTCEPSS rescore
  19. 2026-08-14 08:55 UTCEG score recompute
  20. 2026-08-14 08:55 UTCGHSA enrichment
  21. 2026-08-13 22:00 UTCEPSS rescore
  22. 2026-08-13 10:22 UTCEG score recompute
  23. 2026-08-13 10:22 UTCGHSA enrichment
  24. 2026-08-12 13:51 UTCEPSS rescore
  25. 2026-08-12 11:49 UTCEG score recompute
  26. 2026-08-12 11:49 UTCGHSA enrichment
  27. 2026-08-11 13:15 UTCEG score recompute
  28. 2026-08-11 13:15 UTCGHSA enrichment
  29. 2026-08-11 00:00 UTCEPSS rescore
  30. 2026-08-10 14:42 UTCGHSA enrichment
  31. 2026-08-09 16:08 UTCEG score recompute
  32. 2026-08-09 16:08 UTCGHSA enrichment
  33. 2026-08-09 13:46 UTCEPSS rescore
  34. 2026-08-08 17:36 UTCEG score recompute
  35. 2026-08-08 17:36 UTCGHSA enrichment
  36. 2026-08-08 16:37 UTCEPSS rescore
  37. 2026-08-07 19:03 UTCEG score recompute
  38. 2026-08-07 19:03 UTCGHSA enrichment
  39. 2026-08-06 20:30 UTCEG score recompute
  40. 2026-08-06 20:30 UTCGHSA enrichment
  41. 2026-08-06 13:47 UTCEPSS rescore
  42. 2026-08-05 21:57 UTCEG score recompute
  43. 2026-08-05 21:57 UTCGHSA enrichment
  44. 2026-08-05 19:17 UTCEPSS rescore
  45. 2026-08-04 23:24 UTCEG score recompute
  46. 2026-08-04 23:24 UTCGHSA enrichment
  47. 2026-08-04 15:10 UTCEPSS rescore
  48. 2026-08-04 10:39 UTCEPSS rescore
  49. 2026-08-04 00:51 UTCEG score recompute
  50. 2026-08-04 00:51 UTCGHSA enrichment
  51. 2026-08-03 10:36 UTCEPSS rescore
  52. 2026-08-03 02:18 UTCGHSA enrichment
  53. 2026-08-02 03:45 UTCEG score recompute
  54. 2026-08-02 03:45 UTCGHSA enrichment
  55. 2026-08-02 02:27 UTCEPSS rescore
  56. 2026-08-01 05:10 UTCEG score recompute
  57. 2026-08-01 05:10 UTCGHSA enrichment
  58. 2026-08-01 04:16 UTCEPSS rescore
  59. 2026-07-31 03:52 UTCEG score recompute
  60. 2026-07-31 03:52 UTCGHSA enrichment
  61. 2026-07-30 16:28 UTCEPSS rescore
  62. 2026-07-30 03:08 UTCEG score recompute
  63. 2026-07-30 03:08 UTCGHSA enrichment
  64. 2026-07-30 01:30 UTCEPSS rescore
  65. 2026-07-29 01:46 UTCEG score recompute
  66. 2026-07-29 01:46 UTCGHSA enrichment
  67. 2026-07-28 15:37 UTCEPSS rescore
  68. 2026-07-27 18:07 UTCEG score recompute
  69. 2026-07-27 18:07 UTCGHSA enrichment
  70. 2026-07-26 17:42 UTCEG score recompute
  71. 2026-07-26 17:41 UTCGHSA enrichment
  72. 2026-07-26 14:54 UTCEPSS rescore
  73. 2026-07-25 14:18 UTCEPSS rescore
  74. 2026-07-24 14:18 UTCEPSS rescore
  75. 2026-07-23 14:18 UTCEPSS rescore

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 0% probability of exploitation in the next 30 days, which ranks it in the top 78.4% of all scored CVEs.
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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