CVE-2026-33661

HIGHNVD 7.58.6
EchelonGraph scoreMEDIUM confidence

“▲” beside the score: it is higher than NVD's CVSS score.

Score 8.6 from GitHub Security Advisory (severity: HIGH) published 2026-03-25. NVD baseline CVSS 7.5; sources differ by 1.1.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Elevated

Also known asEUVD-2026-16428 (ENISA EUVD) · GHSA-q938-ghwv-8gvc (GitHub Security Advisories)Source: ENISA EUVD

8.6EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 7.5Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

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
8.6HIGHmedium confidence
EG Risk
70
EG Risk 70/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity86% × 45%
Impact severity (EG Severity): CVSS 8.6 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (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: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
45th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (8.6): severity, escalated by confirmed exploitation. This CVE's 8.6 is its impact severity (EG Severity), not escalated.

EG Severity
8.6 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (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)14 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (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

March 26, 2026

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Aug 2, 2026
Patch available. Sources: github_commit, github_release, github.
GitHub advisoryMentions a patch (unverified)

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

Vendor Advisories for CVE-2026-33661(1)

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

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
composeryansongda/pay @ 3.7.20 (fixes <= 3.7.19)—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFix by version rangeDependents
yansongda/payv0.5.0 ... v3.7.9 (253 versions)
  • every version up to 3.7.20: fixed in 3.7.20
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 33× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 129 rows on record for this CVE, as 97 entries (3 repeats merged).

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 3 repeat rows among the latest 100 are merged into the row they repeat. The 29 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:52 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  2. 2026-11-12 16:33 UTCEPSS rescoreEPSS 0.5% · 45th percentile
  3. 2026-11-11 16:39 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  4. 2026-11-10 16:43 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  5. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  6. 2026-11-09 15:15 UTCEchelonGraph re-scored
  7. 2026-11-09 15:15 UTCGHSA enrichmentGHSA-q938-ghwv-8gvc · GitHub severity HIGH · GitHub CVSS 8.6
  8. 2026-11-08 16:39 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  9. 2026-11-07 16:38 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  10. 2026-11-06 16:37 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  11. 2026-11-05 16:37 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  12. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  13. 2026-11-03 16:47 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  14. 2026-11-03 01:42 UTCEchelonGraph re-scored
  15. 2026-11-03 01:42 UTCGHSA enrichmentGHSA-q938-ghwv-8gvc · GitHub severity HIGH · GitHub CVSS 8.6
  16. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  17. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  18. 2026-11-01 07:53 UTCGHSA enrichmentGHSA-q938-ghwv-8gvc · GitHub severity HIGH · GitHub CVSS 8.6
  19. 2026-11-01 07:53 UTCEchelonGraph re-scored▲ 1.10
  20. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  21. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  22. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  23. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  24. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  25. 2026-10-27 12:10 UTCEchelonGraph re-scored
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  1. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  2. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  3. 2026-10-25 14:34 UTCEchelonGraph re-scored
  4. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  5. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  6. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.7% · 51st percentile
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  8. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  9. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  10. 2026-10-19 05:21 UTCEchelonGraph re-scored
  11. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  12. 2026-10-18 03:46 UTCEchelonGraph re-scored
  13. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  14. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  15. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.7% · 50th percentile
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  17. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  18. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  19. 2026-10-12 15:46 UTCEchelonGraph re-scored
  20. 2026-10-11 19:55 UTCEchelonGraph re-scored
  21. 2026-10-11 17:08 UTCEchelonGraph re-scored
  22. 2026-10-11 14:35 UTCEchelonGraph re-scored
  23. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  24. 2026-10-11 04:01 UTCOSV refresh
  25. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  26. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  27. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  28. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.7% · 50th percentile
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  34. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  35. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  36. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  37. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  38. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  39. 2026-09-21 16:19 UTCOSV refresh
  40. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  41. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  42. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.5% · 41st percentile
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  44. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 41st percentile
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  46. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 41st percentile
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  55. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  56. 2026-09-02 13:14 UTCOSV refresh
  57. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 40th percentile
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  59. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 40th percentile
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Frequently asked(5)

What is CVE-2026-33661?
CVE-2026-33661 is a high-severity vulnerability; its CVE record was 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 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…
When was the CVE record for CVE-2026-33661 published?
The CVE record for CVE-2026-33661 was published on March 26, 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 June 17, 2026; the record at its source may have been updated since.
Is CVE-2026-33661 actively exploited?
CVE-2026-33661 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (45th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-33661?
CVE-2026-33661 has a CVSS v3 base score of 7.5 (NVD). EchelonGraph synthesises NVD + FIRST EPSS + GHSA into a combined EG score of 8.6 (HIGH).
How do I remediate CVE-2026-33661?
A fix for CVE-2026-33661 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-33661 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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