---
id: CVE-2026-49819
title: UpSnap is a wake on lan web app
summary: >-
  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-superu…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-78
  - CWE-269
  - CWE-306
  - CWE-862
vendor: seriousm4x
product: UpSnap
affected:
  - 'UpSnap >= 4.4.1, < 5.4.0'
published: '2026-08-13'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:02:22.660'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-49819'
references:
  - url: 'https://github.com/seriousm4x/UpSnap/releases/tag/5.4.0'
    label: security-advisories@github.com
  - url: >-
      https://github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq
    label: security-advisories@github.com
  - url: >-
      https://github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-08-13T13:08:41.648461Z'
ingestedAt: '2026-09-13T14:51:45.950Z'
epss: 0.0108
epssPercentile: 0.63618
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.