CVE-2023-35838
Wireguard 0.5.3
Raw vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-35838 is a medium-severity Externally Controlled Reference to a Resource in Another Sphere (CWE-610) vulnerability in Wireguard Wireguard. Its CVSS base score is 5.7 (Medium).
Operationally, ranked in the top 48% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-39833
Vulnerability Data
The WireGuard client 0.5.3 on Windows insecurely configures the operating system and firewall such that traffic to a local network that uses non-RFC1918 IP addresses is blocked. This allows an adversary to trick the victim into blocking IP traffic to…
more
selected IP addresses and services even while the VPN is enabled. NOTE: the tunnelcrack.mathyvanhoef.com website uses this CVE ID to refer more generally to "LocalNet attack resulting in the blocking of traffic" rather than to only WireGuard.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Limits impact of an externally controlled reference to a primary information resource by switching to an identified alternative.
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.
Secure development lifecycle mandates validation of all external references to prevent uncontrolled resource access.
A.8.26 only requires that security requirements (including those that could address sphere separation) be identified and specified during development or acquisition; it does not itself enforce, implement or mandate any mechanism that stops external references from resolving outside the intended sphere, so the weakness remains exploitable.
A.8.27 mandates security-by-design principles (least privilege, default-deny, distrust-external-input, fail-securely, zero-trust verification) plus design reviews that can catch and stop many externally-controlled cross-sphere references before they reach production, but leaves a bounded remainder (e.g. runtime name resolution, configuration-driven references, or supplier code not covered by the contract) that can still be present and exploitable.
Secure coding standards require input validation and canonicalization to block externally controlled resource references.
Security testing can detect instances of the weakness but does not prevent it at design or coding time.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.
- No fine-grained STIG row for CWE-610, a class-level weakness, and none of its children carries one either.