UpSnap - Unauthenticated Initial-Superuser Takeover Chains to Root RCE via wake_cmd (CVE-2026-49819) | HOL Guard CVE

Critical · CVSS 9.8CVE-2026-49819

UpSnap - Unauthenticated Initial-Superuser Takeover Chains to Root RCE via wake_cmd

Answer in brief

CVE-2026-49819 records a Critical severity (CVSS 9.8) vulnerability in UpSnap - Unauthenticated Initial-Superuser Takeover Chains to Root RCE via wake_cmd. The current sources do not mark it as known exploited. The current feed maps seriousm4x/UpSnap (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 12, 2026Updated Sep 9, 2026Source checked Sep 27, 2026First seen by HOL Aug 12, 2026Material review Sep 9, 2026

Upstream Advisory

Key facts

Risk: Critical · CVSS 9.8
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

CVSS is 9.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps seriousm4x/UpSnap (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
seriousm4x/UpSnapgeneric	>= 4.4.1, < 5.4.0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for seriousm4x/UpSnap.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 12, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 9, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 12, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.