CVE-2026-49819

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.

CVSS 3.1

9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

1.1% chance of exploitation in the next 30 days; higher than 64% of CVEs (scores of 2026-10-25)

CWEs

CWE-78, CWE-269, CWE-306, CWE-862

Published

2026-08-13

Modified

2026-10-24

Record from

the NVD, synced 2026-10-24

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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