CVE-2026-34209

HIGH7.5

mppx: Tempo has a session close voucher bypass vulnerability due to settled amount equality

Published Mar 31, 2026

Modified 3 weeks ago

Details

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.

References

WEB

https://github.com/wevm/mppx/commit/94088246ee18f21b5d6be40d9e7a464f5a280bfb

WEB

https://github.com/wevm/mppx/releases/tag/mppx@0.4.11

WEB

https://github.com/wevm/mppx/security/advisories/GHSA-mv9j-8jvg-j8mr

ADVISORY

https://www.cve.org/CVERecord?id=CVE-2026-34209

CVSS Analysis

CVSS v3.1

7.5