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CVE-2026-34063

network-libp2p: Peer can crash the node by opening discovery protocol substream twice

7.5 High

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.35%Up 0.3 points since Apr 23, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.5

network-libp2p: Peer can crash the node by opening discovery protocol substream twice

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.

Record
CVE-2026-34063
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-617
Updated
2026-11-02
EUVDEUVD-2026-25058 7.5

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.

Record
EUVD-2026-25058
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
NVD 7.5

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.

Record
CVE-2026-34063
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-617
Updated
2026-11-02
OSV 7.5

network-libp2p: Peer can crash the node by opening discovery protocol substream twice

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.

Record
CVE-2026-34063
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-617
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-34063 is a high vulnerability (CVSS 7.5) in Nimiq Network-libp2p, published April 22, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.35%, the 29th percentile. No source names a fixed version.

References

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