OS Command Injection in UpSnap (CVE-2026-49819)
Summary
OS command injection in UpSnap (CVE-2026-49819). Successful exploitation can lead to full system takeover. Exploitable via POST /api/upsnap/init-superuser.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-49819 has been found in UpSnap.
Attackers can target a specific entry point like POST /api/upsnap/init-superuser over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "UpSnap CVE-2026-49819" on the vendor's site.
CVE-2026-49819 (UpSnap) — CWE-78 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /api/upsnap/init-superuser / pb.HandlerInitSuperuser
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
OS command injection (CWE-78) exists in UpSnap. Attackers reach the vulnerable code path via POST /api/upsnap/init-superuser without authentication.
Check the vendor advisory for the affected versions of UpSnap. Attack surface: POST /api/upsnap/init-superuser / pb.HandlerInitSuperuser.
Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /api/upsnap/init-superuser requests with malformed payloads or SQL meta-characters. Run grep -r 'UpSnap' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'UpSnap' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
UpSnapを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'POST /api/upsnap/init-superuser' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/upsnap/init-superuserへの異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Post-deployment verification verify
Replay attack against POST /api/upsnap/init-superuser on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。