high7.5
CVE-2026-34209
mppx: Tempo has a session close voucher bypass vulnerability due to settled amount equality
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | mppx | < 0.4.11 | 0.4.11 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Wevm | Mppx | before 0.4.11 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-mv9j-8jvg-j8mr
- https://github.com/wevm/mppx/security/advisories/GHSA-mv9j-8jvg-j8mr
- https://github.com/wevm/mppx/commit/94088246ee18f21b5d6be40d9e7a464f5a280bfb
- https://github.com/wevm/mppx/releases/tag/mppx@0.4.11
- https://nvd.nist.gov/vuln/detail/CVE-2026-34209