RCE in Seriousm4x Upsnap
CVE-2026-49819
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.
Vulnerability class: Command Injection (OS Command Injection)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.011 (63.7th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 64th percentile — 63.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.011 · change: +0.005
Affected products
- Seriousm4x Upsnap — versions >= 4.4.1, < 5.4.0
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-49819?
- CVE-2026-49819 is a critical-severity vulnerability in Seriousm4x Upsnap, classified under OS Command Injection. CVSS score: 9.8/10. Published 2026-08-13.
- How severe is CVE-2026-49819?
- Critical severity. CVSS v3 base score is 9.8 out of 10.