CVE-2026-18391

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-12. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this weekElevated
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: Elevated riskExposed: 0

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

The WooCommerce Subscriptions WordPress plugin before 9.1.0 does not validate user input before unserializing it on stores with High-Performance Order Storage enabled, leading to a PHP Object Injection issue which unauthenticated users can escalate to Remote Code Execution via a gadget chain present in the bundled dependencies.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
75(Attend)
EG Risk 75/100SSVC: 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
Severity98% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
48%
KEV
Not listed

Published

August 12, 2026

Last Modified

August 26, 2026

Advisory Details (1)

Auto-updated Sep 16, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

WooCommerce Subscriptions < 9.1.0 – Unauthenticated RCE via PHP Object Injection | CVE 2026-18391 | Plugin Vulnerabilities

https://wpscan.com/vulnerability/191f76cf-e5bd-4a37-ac1c-9187cea2aa27/

Vendor Advisories for CVE-2026-18391(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 45× in last 7d / 208× 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 299 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-18391?
CVE-2026-18391 is a critical vulnerability published on August 12, 2026. The WooCommerce Subscriptions WordPress plugin before 9.1.0 does not validate user input before unserializing it on stores with High-Performance Order Storage enabled, leading to a PHP Object Injection issue which unauthenticated users can escalate to Remote Code Execution via a gadget chain…
When was CVE-2026-18391 disclosed?
CVE-2026-18391 was first published in the National Vulnerability Database on August 12, 2026, with the most recent update on August 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-18391 actively exploited?
CVE-2026-18391 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 52.3% of all scored CVEs.
What is the CVSS score of CVE-2026-18391?
CVE-2026-18391 has a CVSS v3.1 base score of 9.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-18391?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-18391, 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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