FKIE_CVE-2026-49819

Vulnerability from fkie_nvd - Published: 2026-08-13 00:17 - Updated: 2026-09-09 21:02
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
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.
References
security-advisories@github.comhttps://github.com/seriousm4x/UpSnap/releases/tag/5.4.0
security-advisories@github.comhttps://github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "UpSnap",
          "vendor": "seriousm4x",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.4.1, \u003c 5.4.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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 \u003e 0` count check \u2014 a condition that is false on every fresh install \u2014 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."
    }
  ],
  "id": "CVE-2026-49819",
  "lastModified": "2026-09-09T21:02:22.660",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-49819",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-13T13:08:41.648461Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-13T00:17:32.747",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/seriousm4x/UpSnap/releases/tag/5.4.0"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-78"
        },
        {
          "lang": "en",
          "value": "CWE-269"
        },
        {
          "lang": "en",
          "value": "CWE-306"
        },
        {
          "lang": "en",
          "value": "CWE-862"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}



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