CVE-2026-34209
High
Description
mppx is a TypeScript interface for machine payments protocol. Prior to version 0.4.11, the tempo/session cooperative close handler validated the close voucher amount using "<" instead of "<=" against the on-chain settled amount. An attacker could submit a close voucher exactly equal to the settled amount, which would be accepted without committing any new funds, effectively closing or griefing the channel for free. This issue has been patched in version 0.4.11.
SeverityHigh
CVSS7.5
Exploit probability—
ProductWevm Mppx
PublishedMar 31, 2026
First seenMar 31, 2026
Weakness typeCWE-294CWE-294
How to fix
Update
- wevm mppx0.4.11 or later
- mppx0.4.11 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| wevm mppx | v < 0.4.11 | 0.4.11 |
| mppxnpm | v < 0.4.11 | 0.4.11 |
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