CVE-2026-49819: UpSnap - Unauthenticated Initial-Superuser Takeover Chains to Root RCE via wake_cmd
UpSnap is a wake on lan web app. Versions 4.4.1 through 5.3.5 are vulnerable to a missing-authentication / privilege-escalation chain in pb.HandlerInitSuperuser (backend/pb/handlers.go:249), reachable as POST /api/upsnap/init-superuser. The vulnerable code lacks any authentication, setup token, IP allow-list, or rate limit and is gated only by a totalSuperusers > 0 count check — a condition that is false on every fresh install — allowing an unauthenticated network-adjacent attacker to register the initial superuser account, receive a long-lived JWT, and pivot to root remote code execution at backend/networking/wake.go:43 (exec.CommandContext(ctx, "/bin/sh", "-c", wakecmd)). Version 5.4.0 fixes the issue.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
UpSnapto a version that resolves this vulnerability.Fixed in 5.4.0 - Compensating control
Restrict access to the management/initialization endpoint by network controls (e.g., firewall/ACL) so that only trusted clients can reach POST /api/upsnap/init-superuser.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-49819?
CVE-2026-49819 has a critical severity rating of 9.8.
How do I fix CVE-2026-49819?
To fix CVE-2026-49819, update UpSnap to version 5.4.0 or later.
What are the risks associated with CVE-2026-49819?
CVE-2026-49819 exposes systems to unauthenticated initial-superuser takeover and root remote code execution.
Which versions of UpSnap are affected by CVE-2026-49819?
Versions 4.4.1 through 5.3.5 of UpSnap are vulnerable to CVE-2026-49819.
What type of vulnerability is CVE-2026-49819?
CVE-2026-49819 is classified as an OS Command Injection vulnerability.