CVE-2026-34209
HIGHmppx: Tempo has a session close voucher bypass vulnerability due to settled amount equality
Title source: cnaDescription
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 (3)
Scores
CVSS v3
7.5
EPSS
0.0001
EPSS Percentile
1.7%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-294
Status
published
Products (2)
npm/mppx
0 - 0.4.11npm
wevm/mppx
< 0.4.11 (2 CPE variants)
Published
Mar 31, 2026
Tracked Since
Mar 31, 2026