EUVD-2026-56127
GHSA-62g2-q3w2-xf47
Severity by source
AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Network-reachable, low-complexity header spoof needs only a low-priv account (PR:L); scope changes (S:C) because admin control extends to managed endpoints, yielding high confidentiality and integrity impact.
Primary rating from Vendor (rapid7).
CVSS VectorVendor: rapid7
Lifecycle Timeline
3DescriptionCVE.org
An authenticated attacker can spoof another GUI user's identity by sending their request with the custom header \"Grpc-Metadata-USER\". This can lead to an account takeover attack from a user with low privileges to administrator.
AnalysisAI
Privilege escalation to administrator in Rapid7 Velociraptor (all versions before 0.77.2) allows an authenticated low-privileged GUI user to impersonate any other user, including admins, by supplying a crafted 'Grpc-Metadata-USER' header, resulting in full account takeover. The flaw stems from the gRPC/GUI layer trusting a client-supplied identity header instead of the authenticated session. No public exploit has been identified at time of analysis, and it is not listed in CISA KEV, but the fix is trivial to reverse-engineer once the header name is known.
Technical ContextAI
Velociraptor is an open-source digital forensics and incident response (DFIR) platform that lets analysts hunt across and execute collections on large fleets of managed endpoints through a web GUI backed by a gRPC API. The vulnerability is a CWE-290 (Authentication Bypass by Spoofing) issue: the GUI/gRPC front end derives the acting user's identity from a client-controllable 'Grpc-Metadata-USER' metadata header rather than binding actions to the server-validated authenticated session. Because gRPC metadata is passed through as request context, any authenticated caller can override the effective username field, and the authorization layer then grants the impersonated user's permissions. The affected component is the Rapid7 Velociraptor application (cpe:2.3:a:rapid7:velociraptor).
RemediationAI
Vendor-released patch: upgrade to Velociraptor 0.77.2 or later, which is the definitive fix; consult the vendor advisory at http://docs.velociraptor.app/announcements/advisories/cve-2026-18972/. Until the upgrade is applied, restrict who can reach the GUI/gRPC front end - place it behind a VPN or IP allowlist and terminate access at a reverse proxy that strips or rejects any client-supplied 'Grpc-Metadata-USER' header before it reaches the Velociraptor server (this is safe because legitimate clients do not need to set that header, though a misconfigured proxy that fails to strip it leaves the bypass fully open). As a secondary control, minimize the number of low-privilege GUI accounts and audit existing accounts and recent user activity for signs of impersonation, since any authenticated user is a potential launch point.
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Same weakness CWE-290 – Authentication Bypass by Spoofing
View allSame technique Authentication Bypass
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External POC / Exploit Code
Leaving vuln.today