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

> Unauthenticated attackers can create the initial superuser account and achieve root remote code execution via command injection in UpSnap.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Aug 2026
- **Updated:** 13 Aug 2026
- **Also known as:** GHSA-w4jr-728f-5jhq

## What is CVE-2026-49819?

CVE-2026-49819 is a critical authentication bypass vulnerability in seriousm4x UpSnap, published on 12 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-862 (Missing Authorization), CWE-78 (Improper Neutralization of Special Elements used in an OS Command), CWE-306 (Missing Authentication for Critical Functionality), CWE-269 (Improper Privilege Management)

## Which versions are affected by CVE-2026-49819?


## How do I fix CVE-2026-49819?

No fix has been published for CVE-2026-49819 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-49819 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49819 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49819 and fix it if it is affected.

What it is: CVE-2026-49819 is a critical authentication bypass vulnerability in seriousm4x UpSnap, published on 12 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49819 exists.

Affected product: seriousm4x UpSnap. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-49819/ (Markdown: https://insights.sbomify.com/CVE-2026-49819/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49819
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49819
- OSV: https://osv.dev/vulnerability/CVE-2026-49819

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49819/
Summaries are generated and may contain mistakes; the official description above is the record.