How severe is CVE-2026-34063?

CVE-2026-34063 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 none, and availability high.

Is CVE-2026-34063 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-34063?

CVE-2026-34063 affects Nimiq Nimiq Proof-of-stake. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-34063?

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-2026-34063 have an EU (EUVD) identifier?

Yes. CVE-2026-34063 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-25058.

When was CVE-2026-34063 published?

CVE-2026-34063 was published on 2026-04-22 and last updated on 2026-06-17.

CVE-2026-34063

CVE-2026-34063 is a high-severity vulnerability in Nimiq Nimiq Proof-of-stake 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-617.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (27th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-25058
Weakness: CWE-617
Affected product: Nimiq Nimiq Proof-of-stake
Published: 2026-04-22
Last modified: 2026-06-17

Description

Nimiq's network-libp2p is a Nimiq network implementation based on libp2p. Prior to version 1.3.0, `network-libp2p` discovery uses a libp2p `ConnectionHandler` state machine. the handler assumes there is at most one inbound and one outbound discovery substream per connection. if a remote peer opens/negotiate the discovery protocol substream a second time on the same connection, the handler hits a `panic!(\"Inbound already connected\")` / `panic!(\"Outbound already connected\")` path instead of failing closed. This causes a remote crash of the networking task (swarm), taking the node's p2p networking offline until restart. The patch for this vulnerability is formally released as part of v1.3.0. No known workarounds are available.

Frequently asked questions

What is CVE-2026-34063?: Nimiq's network-libp2p is a Nimiq network implementation based on libp2p. Prior to version 1.3.0, `network-libp2p` discovery uses a libp2p `ConnectionHandler` state machine. the handler assumes there is at most one inbound and one outbound discovery substream per connection. if a remote peer opens/negotiate the discovery protocol substream a second time on the same connection, the handler hits a `panic!(\"Inbound already connected\")` / `panic!(\"Outbound already connected\")` path instead of failing closed. This causes a remote crash of the networking task (swarm), taking the node's p2p networking offline until restart. The patch for this vulnerability is formally released as part of v1.3.0. No known workarounds are available.
How severe is CVE-2026-34063?: CVE-2026-34063 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 none, and availability high.
Is CVE-2026-34063 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-34063?: CVE-2026-34063 affects Nimiq Nimiq Proof-of-stake. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-34063?: 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-2026-34063 have an EU (EUVD) identifier?: Yes. CVE-2026-34063 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-25058.
When was CVE-2026-34063 published?: CVE-2026-34063 was published on 2026-04-22 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nimiq:nimiq_proof-of-stake:*:*:*:*:*:rust:*:*

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