Netmaker: Authorization bypass in updateExtClient allows cross-network access
Summary
Netmaker up to and including 1.7.0 does not restrict the updateExtClient handler to the requested network. A user with external client permissions on one network can modify external clients on other networks. The attacker can replace public keys, disable clients and obtain WireGuard private keys. Exploitation requires a valid account with external client rights, and no user interaction is needed.
Affected
- Netmaker 0 up to and including 1.7.0 (per the CVE record)
- Impact: confidentiality and integrity of external clients on other networks
Fixed in
- Unknown. A proposed fix (PR #4153, commit 332d8b9) makes the lookup use the network parameter, but no released version containing it has been confirmed.
Workaround
- Limit external client permissions to trusted administrators and reduce the number of network-scoped accounts.
- Restrict access to the Netmaker controller API to trusted networks.
- No vendor-confirmed workaround is known.
Exploitation
- Not listed as known exploited.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- EPSS 0.00289 (low).
- The issue and fix PR are public and document the root cause, which lowers the effort for an attacker. No public proof of concept was found.
Our recommendation
- Inventory all Netmaker deployments and identify who holds external client permissions.
- Reduce those permissions now to the minimum required.
- Review external clients for unexpected key changes or disabled peers, and rotate WireGuard keys for any client that may have been affected.
- Upgrade as soon as a fixed release is confirmed on the Netmaker releases page.
- Check whether the controller management interface is reachable from the internet.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- VulnCheck advisory www.vulncheck.com
- Netmaker issue #3875 github.com
- Netmaker pull request #4153 github.com
- Netmaker commit 332d8b9 github.com
- Netmaker ext_client.go at v1.7.0 github.com
- Netmaker releases github.com
- NixOS nixpkgs issue 577787 github.com
- VulnCheck EPSS via Vulners vulners.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 00:46.
Original description (NVD)
Netmaker through 1.7.0 contains an authorization bypass vulnerability in the updateExtClient handler that allows network-scoped users to modify external clients on other networks. Attackers with external client permissions on one network can send PUT requests to /api/extclients/{network}/{clientid} to replace public keys, disable clients, and obtain WireGuard private keys.
NVD references (6)
- https://github.com/gravitl/netmaker
- https://github.com/gravitl/netmaker/blob/v1.7.0/controllers/ext_client.go#L879
- https://github.com/gravitl/netmaker/commit/332d8b9bab030ee65e78b9141259e4e0e80ac4b0
- https://github.com/gravitl/netmaker/issues/3875
- https://github.com/gravitl/netmaker/pull/4153
- https://www.vulncheck.com/advisories/netmaker-through-1.7.0-authorization-bypass-via-updateextclient-unscoped…
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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