What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-13 · updated 2026-10-24
• Weakness: CWE-78

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.

Affected products

• seriousm4x UpSnap: from 4.4.1, < 5.4.0

References

• https://github.com/seriousm4x/UpSnap/releases/tag/5.4.0
• https://github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq
• https://github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq

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