CVE-2026-34063
Nimiq Proof-Of-Stake ≤ 1.3.0
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HSummary
CVE-2026-34063 is a high-severity Reachable Assertion (CWE-617) vulnerability in Nimiq Nimiq Proof-Of-Stake. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 28th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-34063 affects Nimiq's network-libp2p, a Nimiq network implementation based on libp2p, in versions prior to 1.3.0. The vulnerability resides in the discovery mechanism, which uses a libp2p ConnectionHandler state machine that assumes at most one inbound and one outbound discovery substream per connection. If a remote peer opens or negotiates the discovery protocol substream a second time on the same connection, the handler triggers a panic! with messages such as "Inbound already connected" or "Outbound already connected" instead of failing closed, leading to a crash of the networking task (swarm) and taking the node's P2P networking offline until restart. This issue is classified under CWE-617 (Reachable Assertion) with a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).
Any remote peer capable of establishing a connection to the vulnerable node can exploit this flaw with low complexity and no privileges or user interaction required. By simply negotiating a duplicate discovery substream, the attacker triggers the panic, resulting in a denial-of-service that disables the node's P2P networking functionality until manual restart.
The patch is formally released in network-libp2p version 1.3.0, as detailed in the Nimiq core-rs-albatross GitHub commit e0d4e01994f061bf41d3c2835bc74040d3c084f5, pull request #3666, release tag v1.3.0, and security advisory GHSA-74hp-mhfx-m45h. No known workarounds are available.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-25058
Vulnerability Data
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…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation finds reachable assertions during development.
Security engineering principles discourage use of assertions for handling untrusted input.
Validating untrusted inputs structurally prevents attacker data from reaching and triggering assertions.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly prevent unsafe assertions from being coded in reachable paths.
Runtime monitoring of software can detect assertion-triggered crashes as adverse events.
Vulnerability identification processes can discover and record reachable-assertion flaws before deployment.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development can detect reachable assertions before release, reducing the likelihood of exploitation.
Secure development lifecycle mandates defensive coding and input validation that prevent reachable assertions from being triggered by untrusted data.
Application security requirements can specify that assertions must not be reachable from attacker-controlled inputs.
Secure architecture principles discourage the use of assertions for runtime error handling that an attacker could exploit.
Secure coding standards explicitly ban the use of assert() or equivalent statements that can be triggered by external input.