CVE-2026-63428

MEDIUMPre-NVD 5.85.8—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 73% 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
5.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.8Exploit: None knownExposed: 0

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

HeyForm is an open-source form builder. Prior to version 3.0.0-rc.9, completeSubmission accepts a hiddenFields: [{id, name, value}] array from the submitter and stores it verbatim in submission.hiddenFields, without validating the supplied id/name against the form's declared form.hiddenFields schema. An anonymous form submitter can therefore inject arbitrary key/value pairs (including XSS payloads, fake authorization metadata, integration-relevant values) into the stored submission. These fields are subsequently forwarded as-is to every webhook integration registered on the form. Version 3.0.0-rc.9 contains a patch for the issue.

CVSS v3
5.8
EG Score
5.8(medium)
EG Risk
31(Track)
EG Risk 31/100SSVC: 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
Severity58% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
27%
KEV
Not listed

Published

July 20, 2026

Last Modified

July 22, 2026

Advisory Details (2)

Auto-updated Jul 22, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
github Patch Available🟡 PoC Available

completeSubmission persists submitter-supplied hidden fields verbatim without validating against the form's declared hidden-field set · Advisory · heyform/heyform · GitHub

https://github.com/heyform/heyform/security/advisories/GHSA-r7vg-xh87-v4w3
github_commit Patch Available

commit 092e255e9e02 (heyform/heyform)

Patch available: heyform/heyform v3.0.0-rc.9 (contains commit 092e255e9e02)

https://github.com/heyform/heyform/commit/092e255e9e02565de1b3c057f3dad849160952d2

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 44× 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. 2026-09-11 14:53 UTCEPSS rescore
  2. 2026-09-11 09:37 UTCEPSS rescore
  3. 2026-09-11 09:28 UTCEG score recompute
  4. 2026-09-09 11:56 UTCEG score recompute
  5. 2026-09-08 22:01 UTCEPSS rescore
  6. 2026-09-07 22:55 UTCEG score recompute
  7. 2026-09-07 16:01 UTCEPSS rescore
  8. 2026-09-06 13:47 UTCEPSS rescore
  9. 2026-09-06 11:46 UTCEG score recompute
  10. 2026-09-05 15:31 UTCEPSS rescore
  11. 2026-09-05 09:33 UTCEG score recompute
  12. 2026-09-04 05:07 UTCEPSS rescore
  13. 2026-09-02 14:12 UTCEPSS rescore
  14. 2026-09-01 13:54 UTCEPSS rescore
  15. 2026-09-01 04:40 UTCEPSS rescore
  16. 2026-08-31 03:16 UTCEG score recompute
  17. 2026-08-30 19:17 UTCEPSS rescore
  18. 2026-08-30 02:37 UTCEG score recompute
  19. 2026-08-30 01:22 UTCEPSS rescore
  20. 2026-08-28 21:42 UTCEPSS rescore
  21. 2026-08-27 14:25 UTCEPSS rescore
  22. 2026-08-27 11:42 UTCEG score recompute
  23. 2026-08-26 14:46 UTCEPSS rescore
  24. 2026-08-26 04:57 UTCEG score recompute
  25. 2026-08-25 13:49 UTCEPSS rescore
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  1. 2026-08-25 04:22 UTCEG score recompute
  2. 2026-08-23 03:11 UTCEG score recompute
  3. 2026-08-23 00:19 UTCEPSS rescore
  4. 2026-08-22 02:31 UTCEG score recompute
  5. 2026-08-21 23:49 UTCEPSS rescore
  6. 2026-08-21 01:56 UTCEG score recompute
  7. 2026-08-20 22:55 UTCEPSS rescore
  8. 2026-08-20 01:16 UTCEG score recompute
  9. 2026-08-19 17:04 UTCEPSS rescore
  10. 2026-08-19 00:40 UTCEG score recompute
  11. 2026-08-18 13:48 UTCEPSS rescore
  12. 2026-08-17 23:54 UTCEG score recompute
  13. 2026-08-17 13:47 UTCEPSS rescore
  14. 2026-08-16 23:18 UTCEG score recompute
  15. 2026-08-16 14:56 UTCEPSS rescore
  16. 2026-08-15 22:43 UTCEG score recompute
  17. 2026-08-15 01:30 UTCEPSS rescore
  18. 2026-08-14 22:07 UTCEG score recompute
  19. 2026-08-13 22:00 UTCEPSS rescore
  20. 2026-08-12 20:57 UTCEG score recompute
  21. 2026-08-12 13:51 UTCEPSS rescore
  22. 2026-08-11 20:22 UTCEG score recompute
  23. 2026-08-11 00:00 UTCEPSS rescore
  24. 2026-08-09 19:12 UTCEG score recompute
  25. 2026-08-09 13:47 UTCEPSS rescore
  26. 2026-08-08 18:37 UTCEG score recompute
  27. 2026-08-08 16:37 UTCEPSS rescore
  28. 2026-08-07 18:01 UTCEG score recompute
  29. 2026-08-06 17:26 UTCEG score recompute
  30. 2026-08-06 13:47 UTCEPSS rescore
  31. 2026-08-05 19:17 UTCEPSS rescore
  32. 2026-08-05 19:17 UTCEPSS rescore
  33. 2026-08-04 16:15 UTCEG score recompute
  34. 2026-08-04 15:10 UTCEPSS rescore
  35. 2026-08-04 10:39 UTCEPSS rescore
  36. 2026-08-03 15:40 UTCEG score recompute
  37. 2026-08-03 10:36 UTCEPSS rescore
  38. 2026-08-02 15:05 UTCEG score recompute
  39. 2026-08-02 02:27 UTCEPSS rescore
  40. 2026-08-01 14:30 UTCEG score recompute
  41. 2026-08-01 04:16 UTCEPSS rescore
  42. 2026-07-31 13:55 UTCEG score recompute
  43. 2026-07-30 16:28 UTCEPSS rescore
  44. 2026-07-30 13:18 UTCEG score recompute
  45. 2026-07-30 01:30 UTCEPSS rescore
  46. 2026-07-30 01:30 UTCEPSS rescore
  47. 2026-07-29 12:41 UTCEG score recompute
  48. 2026-07-28 15:37 UTCEPSS rescore
  49. 2026-07-28 12:03 UTCEG score recompute
  50. 2026-07-27 14:14 UTCEPSS rescore
  51. 2026-07-27 11:24 UTCEG score recompute
  52. 2026-07-26 14:54 UTCEPSS rescore
  53. 2026-07-26 14:54 UTCEPSS rescore
  54. 2026-07-26 10:47 UTCEG score recompute
  55. 2026-07-25 14:18 UTCEPSS rescore
  56. 2026-07-25 14:18 UTCEPSS rescore
  57. 2026-07-24 14:18 UTCEPSS rescore
  58. 2026-07-24 14:18 UTCEPSS rescore
  59. 2026-07-23 14:18 UTCEPSS rescore
  60. 2026-07-23 14:18 UTCEPSS rescore
  61. 2026-07-23 03:22 UTCEG score recompute
  62. 2026-07-22 23:37 UTCEG score recompute
  63. 2026-07-22 14:08 UTCEPSS rescore
  64. 2026-07-22 14:08 UTCEPSS rescore
  65. 2026-07-21 15:25 UTCEPSS rescore
  66. 2026-07-21 15:25 UTCEPSS rescore
  67. 2026-07-20 16:37 UTCEG score recompute
  68. 2026-07-20 16:03 UTCEG score recompute
  69. 2026-07-20 16:02 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-63428?
CVE-2026-63428 is a medium vulnerability published on July 20, 2026. HeyForm is an open-source form builder. Prior to version 3.0.0-rc.9, completeSubmission accepts a hiddenFields: [{id, name, value}] array from the submitter and stores it verbatim in submission.hiddenFields, without validating the supplied id/name against the form's declared form.hiddenFields…
When was CVE-2026-63428 disclosed?
CVE-2026-63428 was first published in the National Vulnerability Database on July 20, 2026, with the most recent update on July 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63428 actively exploited?
CVE-2026-63428 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 72.6% of all scored CVEs.
What is the CVSS score of CVE-2026-63428?
CVE-2026-63428 has a CVSS v3 base score of 5.8 (NVD).
How do I remediate CVE-2026-63428?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63428, 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.

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