Fee-payer wallet draining via trailing calldata
Published Sep 22, 2026 · Updated Sep 22, 2026
Improper input validation in wevm mppx before 0.8.2 allows remote attackers to drain a server fee-payer wallet via padded calldata. FeePayerPolicy decodes sponsored calldata without rejecting trailing nonzero bytes, so intrinsic calldata cost rises outside its decoded gas-policy checks. A deployment must act as the Tempo fee payer; padding constrained by a tested 16 KB header limit raised the transaction fee to about five times normal.
Summary
What happened
Improper input validation in wevm mppx before 0.8.2 allows remote attackers to drain a server fee-payer wallet via padded calldata. FeePayerPolicy decodes sponsored calldata without rejecting trailing nonzero bytes, so intrinsic calldata cost rises outside its decoded gas-policy checks. A deployment must act as the Tempo fee payer; padding constrained by a tested 16 KB header limit raised the transaction fee to about five times normal.
The record
- CVE
- CVE-2026-63627
- Published
- Sep 22, 2026
- Updated
- Sep 22, 2026
- Vendor
- wevm
- Product
- mppx
- Classifications
- CWE-20
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 22, 2026CVE publishedPublication date reported by the CVE source.
- Sep 22, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.8.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
- mppx padded-calldata Docker PoCfunctional · demonstrated
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Technologies
Your stack
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Your stack
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