CVE-2026-18391

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreHIGH 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(high)
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
45%
KEV
Not listed

Published

August 12, 2026

Last Modified

August 12, 2026

Advisory Details (1)

Auto-updated Aug 19, 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 58× in last 7d / 80× 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. 2026-08-21 03:56 UTCGHSA enrichment
  2. 2026-08-21 00:14 UTCEG score recompute
  3. 2026-08-21 00:14 UTCGHSA enrichment
  4. 2026-08-20 22:55 UTCEPSS rescore
  5. 2026-08-20 20:32 UTCGHSA enrichment
  6. 2026-08-20 16:50 UTCGHSA enrichment
  7. 2026-08-20 13:08 UTCGHSA enrichment
  8. 2026-08-20 09:25 UTCGHSA enrichment
  9. 2026-08-20 05:43 UTCGHSA enrichment
  10. 2026-08-20 02:01 UTCGHSA enrichment
  11. 2026-08-19 22:19 UTCGHSA enrichment
  12. 2026-08-19 18:37 UTCEG score recompute
  13. 2026-08-19 18:37 UTCGHSA enrichment
  14. 2026-08-19 17:03 UTCEPSS rescore
  15. 2026-08-19 14:10 UTCGHSA enrichment
  16. 2026-08-19 10:28 UTCGHSA enrichment
  17. 2026-08-19 06:46 UTCGHSA enrichment
  18. 2026-08-19 02:55 UTCGHSA enrichment
  19. 2026-08-18 22:47 UTCGHSA enrichment
  20. 2026-08-18 18:56 UTCGHSA enrichment
  21. 2026-08-18 15:13 UTCEG score recompute
  22. 2026-08-18 15:13 UTCGHSA enrichment
  23. 2026-08-18 13:48 UTCEPSS rescore
  24. 2026-08-18 10:08 UTCGHSA enrichment
  25. 2026-08-18 06:24 UTCGHSA enrichment
Show 55 more
  1. 2026-08-18 02:42 UTCGHSA enrichment
  2. 2026-08-17 22:59 UTCGHSA enrichment
  3. 2026-08-17 19:15 UTCGHSA enrichment
  4. 2026-08-17 15:11 UTCEG score recompute
  5. 2026-08-17 15:11 UTCGHSA enrichment
  6. 2026-08-17 13:47 UTCEPSS rescore
  7. 2026-08-17 11:29 UTCGHSA enrichment
  8. 2026-08-17 07:47 UTCGHSA enrichment
  9. 2026-08-17 04:05 UTCGHSA enrichment
  10. 2026-08-17 00:23 UTCGHSA enrichment
  11. 2026-08-16 20:41 UTCGHSA enrichment
  12. 2026-08-16 16:59 UTCEG score recompute
  13. 2026-08-16 16:59 UTCGHSA enrichment
  14. 2026-08-16 14:56 UTCEPSS rescore
  15. 2026-08-16 13:17 UTCGHSA enrichment
  16. 2026-08-16 09:34 UTCGHSA enrichment
  17. 2026-08-16 05:52 UTCEG score recompute
  18. 2026-08-16 05:52 UTCGHSA enrichment
  19. 2026-08-16 02:14 UTCEPSS rescore
  20. 2026-08-16 02:11 UTCGHSA enrichment
  21. 2026-08-15 22:29 UTCGHSA enrichment
  22. 2026-08-15 18:47 UTCGHSA enrichment
  23. 2026-08-15 15:05 UTCGHSA enrichment
  24. 2026-08-15 11:23 UTCGHSA enrichment
  25. 2026-08-15 07:41 UTCGHSA enrichment
  26. 2026-08-15 03:59 UTCEG score recompute
  27. 2026-08-15 03:59 UTCGHSA enrichment
  28. 2026-08-15 01:30 UTCEPSS rescore
  29. 2026-08-15 00:16 UTCGHSA enrichment
  30. 2026-08-14 20:34 UTCGHSA enrichment
  31. 2026-08-14 16:52 UTCGHSA enrichment
  32. 2026-08-14 13:03 UTCGHSA enrichment
  33. 2026-08-14 09:21 UTCGHSA enrichment
  34. 2026-08-14 05:39 UTCGHSA enrichment
  35. 2026-08-14 01:57 UTCGHSA enrichment
  36. 2026-08-13 22:15 UTCEG score recompute
  37. 2026-08-13 22:15 UTCGHSA enrichment
  38. 2026-08-13 22:00 UTCEPSS rescore
  39. 2026-08-13 18:33 UTCGHSA enrichment
  40. 2026-08-13 14:51 UTCGHSA enrichment
  41. 2026-08-13 11:09 UTCGHSA enrichment
  42. 2026-08-13 07:27 UTCGHSA enrichment
  43. 2026-08-13 03:45 UTCGHSA enrichment
  44. 2026-08-13 00:03 UTCEG score recompute
  45. 2026-08-13 00:03 UTCGHSA enrichment
  46. 2026-08-12 20:21 UTCEG score recompute
  47. 2026-08-12 20:21 UTCGHSA enrichment
  48. 2026-08-12 19:46 UTCEG score recompute▲ 9.80
  49. 2026-08-12 19:46 UTCGHSA enrichment
  50. 2026-08-12 19:45 UTCMITRE cvelistV5CVSS v3 → 9.8 · severity → CRITICAL
  51. 2026-08-12 13:50 UTCEPSS rescore
  52. 2026-08-12 06:31 UTCGHSA enrichment
  53. 2026-08-12 06:30 UTCNVD update
  54. 2026-08-12 06:06 UTCEG score recompute
  55. 2026-08-12 06:03 UTCMITRE cvelistV5first tracked

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. 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 55.0% 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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