CVE-2026-49819 — UpSnap - Unauthenticated Initial-Superuser Takeover Chains to Root RCE via wake_cmd

Description (CNA)

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", wake_cmd)`). Version 5.4.0 fixes the issue.

Affected (CNA)

Vendor / product	Versions
seriousm4x / UpSnap	affected >= 4.4.1, < 5.4.0

CWE

CWE-78, CWE-269, CWE-306, CWE-862

References

ADP enrichment

CISA-ADP

No English description supplied.

https://github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq