CVE-2026-34209
mppx: Tempo has a session close voucher bypass vulnerability due to settled amount equality
7.5
HIGH
CVSS 3.1
EPSS 0.01%
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.
How to fix CVE-2026-34209
To remediate CVE-2026-34209, upgrade the affected package to a fixed version below.
- —upgrade to 0.4.11 or later
Is CVE-2026-34209 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 0.4.11
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |