CVE-2021-47934

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

Score 5.3 from GitHub Security Advisory published 2026-05-16. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: Elevated riskExposed: 0

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

MyBB Timeline Plugin 1.0 contains cross-site scripting vulnerabilities that allow attackers to inject malicious scripts through thread titles, post content, and user profile fields like Location and Bio. Attackers can also exploit a cross-site request forgery vulnerability in the timeline.php profile action to change a user's cover picture by crafting malicious forms that execute when victims visit affected profiles.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
55(Attend)
EG Risk 55/100SSVC: Attend

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
Severity53% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
14%
KEV
Not listed

Published

May 16, 2026

Last Modified

May 18, 2026

Advisory Details (3)

Auto-updated May 16, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic

MyBB Timeline Plugin 1.0 Cross-Site Scripting and CSRF | Advisories | VulnCheck

https://www.vulncheck.com/advisories/mybb-timeline-plugin-cross-site-scripting-and-csrf
generic🟡 PoC Available

MyBB Timeline Plugin 1.0 - Persistent Cross-Site Scripting - PHP webapps Exploit

https://www.exploit-db.com/exploits/49467
generic
https://community.mybb.com/mods.php?action=view&pid=1428

Vendor Advisories for CVE-2021-47934(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 6× in last 7d / 49× 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 227 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2021-47934?
CVE-2021-47934 is a medium vulnerability published on May 16, 2026. MyBB Timeline Plugin 1.0 contains cross-site scripting vulnerabilities that allow attackers to inject malicious scripts through thread titles, post content, and user profile fields like Location and Bio. Attackers can also exploit a cross-site request forgery vulnerability in the timeline.php…
When was CVE-2021-47934 disclosed?
CVE-2021-47934 was first published in the National Vulnerability Database on May 16, 2026, with the most recent update on May 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-47934 actively exploited?
CVE-2021-47934 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 86.0% of all scored CVEs.
What is the CVSS score of CVE-2021-47934?
CVE-2021-47934 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2021-47934?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-47934, 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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