CVE-2026-33661

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.5%, top 59% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: None knownExposed: 0

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

Pay is an open-source payment SDK extension package for various Chinese payment services. Prior to version 3.7.20, the verify_wechat_sign() function in src/Functions.php unconditionally skips all signature verification when the PSR-7 request reports localhost as the host. An attacker can exploit this by sending a crafted HTTP request to the WeChat Pay callback endpoint with a Host: localhost header, bypassing the RSA signature check entirely. This allows forging fake WeChat Pay payment success notifications, potentially causing applications to mark orders as paid without actual payment. Version 3.7.20 fixes the issue.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
38(Track)
EG Risk 38/100SSVC: 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
Severity75% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
42%
KEV
Not listed

Published

March 26, 2026

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Aug 2, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
github Patch Available🟡 PoC Available

WeChat Pay callback signature verification bypassed when Host header is localhost · Advisory · yansongda/pay · GitHub

https://github.com/yansongda/pay/security/advisories/GHSA-q938-ghwv-8gvc
github_release Patch Available

v3.7.20

Patch available: yansongda/pay v3.7.20

https://github.com/yansongda/pay/releases/tag/v3.7.20
github_commit Patch Available

commit 26987ebf789f (yansongda/pay)

Patch available: yansongda/pay v3.7.20 (contains commit 26987ebf789f)

https://github.com/yansongda/pay/commit/26987ebf789f1e7f0a85febb640986ab4289fd7f

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFixed inDependents
yansongda/payv0.5.0 ... v3.7.9 (253 versions)3.7.20—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 29× 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. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-17 19:30 UTCEPSS rescore
  4. 2026-09-16 14:08 UTCEPSS rescore
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-15 03:11 UTCEPSS rescore
  7. 2026-09-13 16:47 UTCEPSS rescore
  8. 2026-09-12 15:01 UTCEPSS rescore
  9. 2026-09-11 14:53 UTCEPSS rescore
  10. 2026-09-11 09:37 UTCEPSS rescore
  11. 2026-09-10 09:34 UTCEPSS rescore
  12. 2026-09-08 22:00 UTCEPSS rescore
  13. 2026-09-07 16:01 UTCEPSS rescore
  14. 2026-09-06 13:47 UTCEPSS rescore
  15. 2026-09-04 05:06 UTCEPSS rescore
  16. 2026-09-02 14:11 UTCEPSS rescore
  17. 2026-09-02 13:14 UTCOSV refresh
  18. 2026-09-01 13:53 UTCEPSS rescore
  19. 2026-09-01 04:39 UTCEPSS rescore
  20. 2026-09-01 04:39 UTCEPSS rescore
  21. 2026-08-30 19:17 UTCEPSS rescore
  22. 2026-08-30 01:22 UTCEPSS rescore
  23. 2026-08-28 21:41 UTCEPSS rescore
  24. 2026-08-27 14:25 UTCEPSS rescore
  25. 2026-08-26 14:46 UTCEPSS rescore
Show 39 more
  1. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-24 14:17 UTCEPSS rescore
  3. 2026-08-23 00:19 UTCEPSS rescore
  4. 2026-08-21 23:49 UTCEPSS rescore
  5. 2026-08-20 22:55 UTCEPSS rescore
  6. 2026-08-20 22:55 UTCEPSS rescore
  7. 2026-08-19 17:03 UTCEPSS rescore
  8. 2026-08-18 13:48 UTCEPSS rescore
  9. 2026-08-17 13:47 UTCEPSS rescore
  10. 2026-08-16 14:56 UTCEPSS rescore
  11. 2026-08-16 10:04 UTCEG score recompute
  12. 2026-08-16 02:14 UTCEPSS rescore
  13. 2026-08-15 01:30 UTCEPSS rescore
  14. 2026-08-14 06:23 UTCEG score recompute
  15. 2026-08-13 22:00 UTCEPSS rescore
  16. 2026-08-12 20:40 UTCEG score recompute
  17. 2026-08-12 13:50 UTCEPSS rescore
  18. 2026-08-11 20:48 UTCEG score recompute
  19. 2026-08-11 03:50 UTCEG score recompute
  20. 2026-08-11 00:00 UTCEPSS rescore
  21. 2026-08-09 16:54 UTCEG score recompute
  22. 2026-08-09 13:46 UTCEPSS rescore
  23. 2026-08-09 05:56 UTCEG score recompute
  24. 2026-08-08 16:37 UTCEPSS rescore
  25. 2026-08-08 03:20 UTCEG score recompute
  26. 2026-08-06 18:45 UTCEG score recompute
  27. 2026-08-06 13:46 UTCEPSS rescore
  28. 2026-08-06 00:49 UTCEG score recompute
  29. 2026-08-05 19:17 UTCEPSS rescore
  30. 2026-08-04 15:10 UTCEPSS rescore
  31. 2026-08-04 10:38 UTCEPSS rescore
  32. 2026-08-03 23:14 UTCEG score recompute
  33. 2026-08-03 10:36 UTCEPSS rescore
  34. 2026-08-02 15:15 UTCEG score recompute
  35. 2026-08-02 02:27 UTCEPSS rescore
  36. 2026-08-01 04:16 UTCEPSS rescore
  37. 2026-07-30 16:28 UTCEPSS rescore
  38. 2026-07-30 01:30 UTCEPSS rescore
  39. 2026-07-27 14:20 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-33661?
CVE-2026-33661 is a high vulnerability published on March 26, 2026. Pay is an open-source payment SDK extension package for various Chinese payment services. Prior to version 3.7.20, the verifywechatsign() function in src/Functions.php unconditionally skips all signature verification when the PSR-7 request reports localhost as the host. An attacker can exploit this…
When was CVE-2026-33661 disclosed?
CVE-2026-33661 was first published in the National Vulnerability Database on March 26, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33661 actively exploited?
CVE-2026-33661 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 58.0% of all scored CVEs.
What is the CVSS score of CVE-2026-33661?
CVE-2026-33661 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-33661?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33661, 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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