Review reviewHigh

CVE-2026-34209

wevm mppx

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.

CVSS: 7.5
EPSS: 0.36%
CISA KEV: Not listed
Published: 2026.04.01

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.36%

Technical severityCVSS 7.5

Vulnerability overview

Affected product and versions

Product: wevm mppx
Affected versions: >= < 0.4.11, < 0.4.11
Fixed versions: 0.4.11

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that wevm mppx and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CWE: CWE-294