mppx is a TypeScript interface for machine payments protocol. Prior to 0.8.2, the fee-payer cosigning path in src/tempo/internal/fee-payer.ts copied a client-supplied access_list from a 0x78 FeePayerEnvelope without validating its length or contents. Because EIP-2930 access-list entries consume intrinsic gas even when the listed addresses are never used, a client could add fabricated address-only entries and cause the server fee_payer wallet to pay unnecessary transaction fees. The demonstrated 180-entry list remained within the 500,000 gas policy cap, 16 KB header limit, and RPC simulation budget while increasing the fee by approximately 9.4 times. This issue is fixed in version 0.8.2.
CVE-2026-63628
MEDIUMPre-NVD 6.96.9—Trending — 3 sources updated this week
EchelonGraph scoreMEDIUM confidence
This medium-severity CVE scores 6.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 57% 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, secondary
6.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 6.9Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.9
- EG Score
- 6.9(medium)
- EG Risk
- 36(Track)EG Risk 36/100SSVC: 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 computedSeverity69% × 45%Exploitation1% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 1%
- EPSS %ILE
- 43%
- KEV
- Not listed
Published
September 22, 2026
Last Modified
September 23, 2026
Advisory Details (4)
Auto-updated Sep 22, 2026🔬 Proof of concept available. Patch available. Sources: github_pr, github_commit, github_release, github.
github_release Patch Available
[email protected]
Patch available: wevm/mppx [email protected]
https://github.com/wevm/mppx/releases/tag/[email protected]github_commit Patch Available
commit 24ddcca719ae (wevm/mppx)
Patch available: wevm/mppx [email protected] (contains commit 24ddcca719ae)
https://github.com/wevm/mppx/commit/24ddcca719ae282977d8747309ed1275ea282b25github_pr Patch Available
fix: reject non-canonical fee-payer transactions
Patch available: wevm/mppx [email protected] (PR #602 merged 2026-07-01)
https://github.com/wevm/mppx/pull/602github Patch Available🟡 PoC Available
Gas Draining with access list · Advisory · wevm/mppx · GitHub
https://github.com/wevm/mppx/security/advisories/GHSA-vc9j-9wph-qghjVendor Advisories for CVE-2026-63628(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
npm(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| mppx | — | 0.8.2 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 5× in last 7d / 5× 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.
- 2026-09-23 18:25 UTCEG score recompute
- 2026-09-23 17:54 UTCEPSS rescore
- 2026-09-22 20:32 UTCEG score recompute
- 2026-09-22 19:23 UTCEG score recompute
- 2026-09-22 19:23 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Same CWE
10 shownCWE-20
Frequently asked(5)
What is CVE-2026-63628?
CVE-2026-63628 is a medium vulnerability published on September 22, 2026. mppx is a TypeScript interface for machine payments protocol. Prior to 0.8.2, the fee-payer cosigning path in src/tempo/internal/fee-payer.ts copied a client-supplied accesslist from a 0x78 FeePayerEnvelope without validating its length or contents. Because EIP-2930 access-list entries consume…
When was CVE-2026-63628 disclosed?
CVE-2026-63628 was first published in the National Vulnerability Database on September 22, 2026, with the most recent update on September 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63628 actively exploited?
CVE-2026-63628 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 56.6% of all scored CVEs.
What is the CVSS score of CVE-2026-63628?
CVE-2026-63628 has a CVSS v3 base score of 6.9 (NVD).
How do I remediate CVE-2026-63628?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63628, 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
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-63628
Is Your Infrastructure Affected by CVE-2026-63628?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.