CVE-2026-8809

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-29. the CNA's CVSS baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:wordfence, epss, ghsa
Trending — 3 sources updated this week
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.8Exploit: NoneExposed: 0

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

The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to Privilege Escalation via Validation Bypass in all versions up to and including 0.9.2.5. The vulnerability exists due to the after_validate_save_post() function unconditionally trusting the attacker-controlled _acf_post_id POST parameter — with no authentication or integrity verification — to select a cleanup branch that silently discards all validation errors not prefixed with acfe:. This makes it possible for unauthenticated attackers to suppress both the role allow-list validation error added by acfe_field_user_roles::validate_front_value() and the administrator-role capability guard error added by acfe_module_form_action_user::validate_action(), causing wp_insert_user() to execute with an attacker-supplied administrator role argument and resulting in the creation of a new administrator-level user account. Exploitation requires the target site to expose a public ACFE frontend form configured with a Create User action that maps a role field.

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
52.4%
KEV
Not listed

Published

May 28, 2026

Last Modified

May 29, 2026

References (6)

Vendor Advisories for CVE-2026-8809(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 17× in last 7d / 132× 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 327 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-8809?
CVE-2026-8809 is a critical vulnerability published on May 28, 2026. The Advanced Custom Fields: Extended plugin for WordPress is vulnerable to Privilege Escalation via Validation Bypass in all versions up to and including 0.9.2.5. The vulnerability exists due to the aftervalidatesavepost() function unconditionally trusting the attacker-controlled acfpostid POST…
When was CVE-2026-8809 disclosed?
CVE-2026-8809 was first published in the National Vulnerability Database on May 28, 2026, with the most recent update on May 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-8809 actively exploited?
CVE-2026-8809 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 52.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-8809?
CVE-2026-8809 has a CVSS v4.0 base score of 9.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-8809?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8809, 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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