CVE-2026-16621

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreHIGH confidence

Score 5.3 from GitHub Security Advisory published 2026-08-12. a secondary CVSS source baseline 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: None knownExposed: 0

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

The Payment Gateway for PayPal on WooCommerce WordPress plugin before 9.2.1 does not verify that payment actually succeeded before completing an order in its PayPal return handler: it reads attacker-controlled parameters, performs no amount comparison and no order-ownership check, and completes the order even when the server-side gateway verification fails, allowing an unauthenticated attacker to mark arbitrary orders as paid without paying.

CVSS v3
5.3
EG Score
5.3(high)
EG Risk
39(Track)
EG Risk 39/100SSVC: Track

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
Severity53% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
2%
KEV
Not listed

Published

August 12, 2026

Last Modified

August 12, 2026

Advisory Details (1)

Auto-updated Aug 12, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

Payment Gateway for PayPal on WooCommerce < 9.2.1 – Unauthenticated Payment Bypass via PayPal Advanced Return Handler | CVE 2026-16621 | Plugin Vulnerabilities

https://wpscan.com/vulnerability/76c4cff2-1166-45fe-9517-5eda2d24c35d/

Vendor Advisories for CVE-2026-16621(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Data Freshness Timeline

(refreshed 17× in last 7d / 25× 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. 2026-08-20 22:55 UTCEPSS rescore
  2. 2026-08-20 02:54 UTCEG score recompute
  3. 2026-08-20 02:54 UTCGHSA enrichment
  4. 2026-08-19 17:03 UTCEPSS rescore
  5. 2026-08-19 01:00 UTCEG score recompute
  6. 2026-08-19 01:00 UTCGHSA enrichment
  7. 2026-08-18 13:48 UTCEPSS rescore
  8. 2026-08-17 23:07 UTCGHSA enrichment
  9. 2026-08-16 21:10 UTCEG score recompute
  10. 2026-08-16 21:10 UTCGHSA enrichment
  11. 2026-08-16 14:56 UTCEPSS rescore
  12. 2026-08-16 02:14 UTCEPSS rescore
  13. 2026-08-15 19:17 UTCEG score recompute
  14. 2026-08-15 19:17 UTCGHSA enrichment
  15. 2026-08-15 01:30 UTCEPSS rescore
  16. 2026-08-14 17:24 UTCEG score recompute
  17. 2026-08-14 17:24 UTCGHSA enrichment
  18. 2026-08-13 22:00 UTCEPSS rescore
  19. 2026-08-13 15:30 UTCGHSA enrichment
  20. 2026-08-12 13:37 UTCEG score recompute
  21. 2026-08-12 13:37 UTCGHSA enrichment
  22. 2026-08-12 12:35 UTCEG score recompute
  23. 2026-08-12 12:35 UTCGHSA enrichment
  24. 2026-08-12 11:34 UTCEG score recompute
  25. 2026-08-12 11:33 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-16621?
CVE-2026-16621 is a medium vulnerability published on August 12, 2026. The Payment Gateway for PayPal on WooCommerce WordPress plugin before 9.2.1 does not verify that payment actually succeeded before completing an order in its PayPal return handler: it reads attacker-controlled parameters, performs no amount comparison and no order-ownership check, and completes the…
When was CVE-2026-16621 disclosed?
CVE-2026-16621 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-2026-16621 actively exploited?
CVE-2026-16621 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 98.2% of all scored CVEs.
What is the CVSS score of CVE-2026-16621?
CVE-2026-16621 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-16621?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-16621, 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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