How severe is CVE-2026-34209?

CVE-2026-34209 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2026-34209 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-34209?

CVE-2026-34209 affects Wevm Mppx. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-34209?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-34209 have an EU (EUVD) identifier?

Yes. CVE-2026-34209 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-17455.

When was CVE-2026-34209 published?

CVE-2026-34209 was published on 2026-03-31 and last updated on 2026-06-17.

CVE-2026-34209

CVE-2026-34209 is a high-severity vulnerability in Wevm Mppx with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-294.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (28th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-17455
Weakness: CWE-294
Affected product: Wevm Mppx
Published: 2026-03-31
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-34209?: 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.
How severe is CVE-2026-34209?: CVE-2026-34209 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2026-34209 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-34209?: CVE-2026-34209 affects Wevm Mppx. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-34209?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-34209 have an EU (EUVD) identifier?: Yes. CVE-2026-34209 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-17455.
When was CVE-2026-34209 published?: CVE-2026-34209 was published on 2026-03-31 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:wevm:mppx:*:*:*:*:*:node.js:*:*

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