Vulnerability in Wevm Mppx
CVE-2026-34209
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.
EPSS: 0.004 (28.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
Affected products
- Wevm Mppx — versions < 0.4.11
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Patch, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-34209?
- CVE-2026-34209 is a high-severity vulnerability in Wevm Mppx, classified under Authentication Bypass by Capture-replay. CVSS score: 7.5/10. Published 2026-03-31.
- How severe is CVE-2026-34209?
- High severity. CVSS v3 base score is 7.5 out of 10.