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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-49819
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-13 00:17:32 UTC
Updated2026-08-13 13:19:09 UTC
DescriptionUpSnap 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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.006150000 probability, percentile 0.464480000 (date 2026-08-14)

Problem Types: CWE-78 | CWE-269 | CWE-306 | CWE-862 | CWE-78 CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') | CWE-269 CWE-269: Improper Privilege Management | CWE-306 CWE-306: Missing Authentication for Critical Function | CWE-862 CWE-862: Missing Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Seriousm4x UpSnap affected >= 4.4.1, < 5.4.0 Not specified

References

ReferenceSourceLinkTags
github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/seriousm4x/UpSnap/releases/tag/5.4.0 [email protected] github.com
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