CVE-2026-8809

CRITICALPre-NVD 9.89.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-29. A secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 3 sources updated this week
9.8EG
EchelonGraph verdictPlan mitigationRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.9%CVSS: 9.8Exploit: None knownExposed services: Not assessed

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

The CVE record's CNA (Wordfence) lists hwk-fr Advanced Custom Fields: Extended versions up to and including 0.9.2.5 as affected. No release containing a fix is confirmed on record.

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
9.8CRITICALmedium confidence
EG Risk
59
EG Risk 59/100

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 (value × EchelonGraph’s weight)
Severity98% × 45%
The EG Score, 9.8 of 10.
Exploitation0.9% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.9%
EPSS %ILE
57th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

May 28, 2026

Last Modified

July 21, 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 18× in last 7d / 36× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 97 of 397 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 3 repeat rows among the latest 100 are merged into the row they repeat. The 300 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  2. 2026-10-15 13:52 UTCEG score recompute
  3. 2026-10-15 13:51 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  4. 2026-10-14 16:34 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  5. 2026-10-14 08:46 UTCEG score recompute
  6. 2026-10-14 08:45 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  7. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  8. 2026-10-13 04:16 UTCEG score recompute
  9. 2026-10-13 04:16 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  10. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  11. 2026-10-12 14:49 UTCEG score recompute
  12. 2026-10-12 05:10 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  13. 2026-10-11 19:15 UTCEG score recompute
  14. 2026-10-11 16:32 UTCEG score recompute
  15. 2026-10-11 13:50 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  16. 2026-10-11 13:49 UTCEG score recompute
  17. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  18. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  19. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  20. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  21. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  22. 2026-10-05 17:44 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  23. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  24. 2026-10-01 19:51 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  25. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.9% · 57th percentile
Show 72 more
  1. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  2. 2026-09-27 13:49 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  3. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  4. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.9% · 56th percentile
  5. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  6. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  7. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  8. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  9. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  10. 2026-09-17 19:32 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  11. 2026-09-16 14:09 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  12. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  13. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  14. 2026-09-14 06:29 UTCEG score recompute
  15. 2026-09-14 06:29 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  16. 2026-09-13 16:48 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  17. 2026-09-12 15:02 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  18. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  19. 2026-09-11 09:38 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  20. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  21. 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  22. 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  23. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  24. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  25. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  26. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  27. 2026-08-30 19:18 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  28. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  29. 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  30. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  31. 2026-08-26 14:47 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  32. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  33. 2026-08-25 04:29 UTCEG score recompute
  34. 2026-08-25 04:29 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  35. 2026-08-24 14:18 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  36. 2026-08-23 23:53 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  37. 2026-08-23 18:39 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  38. 2026-08-23 14:21 UTCEG score recompute
  39. 2026-08-23 14:21 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  40. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  41. 2026-08-22 00:41 UTCEG score recompute
  42. 2026-08-22 00:41 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  43. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  44. 2026-08-21 20:22 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  45. 2026-08-21 15:15 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  46. 2026-08-21 02:27 UTCEG score recompute
  47. 2026-08-21 02:27 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  48. 2026-08-20 22:56 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  49. 2026-08-20 21:51 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  50. 2026-08-20 17:32 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  51. 2026-08-20 10:31 UTCEG score recompute
  52. 2026-08-20 10:31 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  53. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  54. 2026-08-18 13:49 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  55. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  56. 2026-08-17 11:15 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  57. 2026-08-17 06:56 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  58. 2026-08-16 15:23 UTCEG score recompute
  59. 2026-08-16 15:23 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  60. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  61. 2026-08-16 11:03 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  62. 2026-08-16 06:45 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  63. 2026-08-16 02:27 UTCEG score recompute
  64. 2026-08-16 02:27 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  65. 2026-08-16 02:15 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  66. 2026-08-15 02:36 UTCEG score recompute
  67. 2026-08-15 02:36 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  68. 2026-08-15 01:31 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  69. 2026-08-14 22:16 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  70. 2026-08-14 17:58 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  71. 2026-08-14 13:34 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8
  72. 2026-08-14 09:15 UTCGHSA enrichmentGHSA-jvvq-c627-79xm · GitHub severity CRITICAL · GitHub CVSS 9.8

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-8809?
CVE-2026-8809 is a critical-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-8809 published?
The CVE record for CVE-2026-8809 was published on May 28, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of July 21, 2026; the record at its source may have been updated since.
Is CVE-2026-8809 actively exploited?
CVE-2026-8809 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.9% probability of exploitation in the next 30 days (57th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-8809?
CVE-2026-8809 has a CVSS base score of 9.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-8809?
No fix for CVE-2026-8809 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The CVE record's CNA (Wordfence) lists hwk-fr Advanced Custom Fields: Extended versions up to and including 0.9.2.5 as affected. No release containing a fix is confirmed on record. The vendor advisories EchelonGraph has for CVE-2026-8809 are linked in the Vendor Advisories panel on this page.

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