CVE-2026-88764

MEDIUMPre-NVD 5.45.4
EchelonGraph scoreHIGH confidence

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

Score 5.4 from GitHub Security Advisory published 2026-09-13. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 5.4; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: CISA-ADP (Vulnrichment) CVSS v3.1, EPSS, GitHub Security Advisory
Trending — 3 sources updated this week
5.4EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 5.4Exploit: 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 Simple Membership WordPress plugin before 4.7.8 does not validate that the membership level supplied in a PayPal payment notification matches the level configured for the paid payment button, allowing members to pay for a lower-priced membership while being granted a higher, more privileged membership level.

CVSS v3
5.4
EG Score
5.4MEDIUMhigh confidence
EG Risk
24
EG Risk 24/100

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)
Severity54% × 45%
The EG Score, 5.4 of 10.
Exploitation0.2% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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, and watch the vendor's advisory for the fix.
EPSS PROB
0.2%
EPSS %ILE
12th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines, and watch the vendor's advisory for the fix.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (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

September 13, 2026

Last Modified

September 14, 2026

Advisory Details (1)

Auto-updated Sep 13, 2026
No fix on record yet.
Web page

Simple Membership < 4.7.8 – Subscriber+ Membership Level Escalation via PayPal Standard subsc_ref | CVE 2026-88764 | Plugin Vulnerabilities

https://wpscan.com/vulnerability/54fdf46e-0385-40a3-b3bc-a862dc0fb03e/

Vendor Advisories for CVE-2026-88764(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 21× in last 7d / 85× 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.

  1. 2026-10-11 19:15 UTCEG score recompute
  2. 2026-10-11 16:32 UTCEG score recompute
  3. 2026-10-11 13:48 UTCEG score recompute
  4. 2026-10-11 06:40 UTCEG score recompute
  5. 2026-10-11 06:39 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  6. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  7. 2026-10-09 23:44 UTCEG score recompute
  8. 2026-10-09 23:44 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  10. 2026-10-08 23:07 UTCEG score recompute
  11. 2026-10-08 23:07 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  12. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  13. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  14. 2026-10-07 12:55 UTCEG score recompute
  15. 2026-10-07 12:55 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  16. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  17. 2026-10-06 12:09 UTCEG score recompute
  18. 2026-10-06 12:09 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  19. 2026-10-05 17:44 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  20. 2026-10-05 11:33 UTCEG score recompute
  21. 2026-10-05 11:33 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  22. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  23. 2026-10-04 10:56 UTCEG score recompute
  24. 2026-10-04 10:55 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  25. 2026-10-03 10:08 UTCEG score recompute
Show 60 more
  1. 2026-10-03 10:08 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  2. 2026-10-02 08:31 UTCEG score recompute
  3. 2026-10-02 08:31 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  4. 2026-10-01 19:51 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  5. 2026-10-01 07:54 UTCEG score recompute
  6. 2026-10-01 07:54 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  7. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  8. 2026-09-30 07:18 UTCEG score recompute
  9. 2026-09-30 07:18 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  10. 2026-09-29 06:41 UTCEG score recompute
  11. 2026-09-29 06:41 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  12. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  13. 2026-09-28 06:04 UTCEG score recompute
  14. 2026-09-28 06:04 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  15. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  16. 2026-09-27 05:27 UTCEG score recompute
  17. 2026-09-27 05:27 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  18. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  19. 2026-09-26 04:48 UTCEG score recompute
  20. 2026-09-26 04:48 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  21. 2026-09-25 04:12 UTCEG score recompute
  22. 2026-09-25 04:12 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  23. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  24. 2026-09-24 03:35 UTCEG score recompute
  25. 2026-09-24 03:35 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  26. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  27. 2026-09-23 02:58 UTCEG score recompute
  28. 2026-09-23 02:58 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  29. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  30. 2026-09-22 02:21 UTCEG score recompute
  31. 2026-09-22 02:21 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  32. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  33. 2026-09-21 01:44 UTCEG score recompute
  34. 2026-09-21 01:44 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  35. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  36. 2026-09-20 01:07 UTCEG score recompute
  37. 2026-09-20 01:07 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  38. 2026-09-19 00:30 UTCEG score recompute
  39. 2026-09-19 00:30 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  40. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  41. 2026-09-17 23:52 UTCEG score recompute
  42. 2026-09-17 23:52 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  43. 2026-09-17 19:32 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  44. 2026-09-16 22:30 UTCEG score recompute
  45. 2026-09-16 22:30 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  46. 2026-09-16 14:09 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  47. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  48. 2026-09-15 21:54 UTCEG score recompute
  49. 2026-09-15 21:54 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  50. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  51. 2026-09-14 21:17 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  52. 2026-09-14 11:58 UTCEG score recompute
  53. 2026-09-14 11:58 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7 · GitHub CVSS 5.4
  54. 2026-09-13 11:21 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7
  55. 2026-09-13 10:50 UTCEG score recomputeFirst assessed: 5.4 MEDIUM
  56. 2026-09-13 10:50 UTCGHSA enrichmentGHSA-cmhf-4mfx-3gf7
  57. 2026-09-13 10:49 UTCMITRE cvelistV5CVSS v3 → 5.4 · severity → MEDIUM
  58. 2026-09-13 06:26 UTCNVD update
  59. 2026-09-13 06:06 UTCEG score recompute
  60. 2026-09-13 06:06 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-88764?
CVE-2026-88764 is a medium-severity vulnerability; its CVE record was published on September 13, 2026. The Simple Membership WordPress plugin before 4.7.8 does not validate that the membership level supplied in a PayPal payment notification matches the level configured for the paid payment button, allowing members to pay for a lower-priced membership while being granted a higher, more privileged…
When was the CVE record for CVE-2026-88764 published?
The CVE record for CVE-2026-88764 was published on September 13, 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 September 14, 2026; the record at its source may have been updated since.
Is CVE-2026-88764 actively exploited?
CVE-2026-88764 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (12th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-88764?
CVE-2026-88764 has a CVSS v3.1 base score of 5.4 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-88764?
No fix for CVE-2026-88764 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 vendor advisories EchelonGraph has for CVE-2026-88764 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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