In short
- CVE-2026-34209 is a HIGH (CVSS 7.5) vulnerability affecting mppx (wevm), mppx.
- Chance of exploitation in the next 30 days (EPSS): 0.37%, higher than 31.2% of all vulnerabilities.
- Fix: update to 0.4.11 or later.
| Package | Affected versions | Patched versions |
|---|
| mppx | < 0.4.11
| 0.4.11
|
| mppx npm | < 0.4.11
| 0.4.11
|
Description
Impact
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.
Patches
Fixed in 0.4.11.
Workarounds
There are no workarounds available for this vulnerability.
NVD 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.
Running one of these products? Scan your site to see whether it exposes a vulnerable version.
Scan my site free