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CVE-2026-76504

Status: AnalyzedCritical (9.8)⚠ Active exploitation

A vulnerability in the API session-based authentication management of Cisco Catalyst SD-WAN Manager could allow an unauthenticated, remote attacker to access an affected system with privileges of the admin user. This vulnerability is due to improper handling of URI encoding in an HTTP request, which allows the request to bypass an authentication rule that is intended to restrict access to a specific API endpoint. An attacker could exploit this vulnerability by sending a crafted HTTP request to the API of the affected system. A successful exploit could allow the attacker to bypass authentication and gain access to the API as the admin user.

CVSS

Exploitation probability (EPSS)

FIRST hasn't scored this CVE yet (usual for very recent or rejected CVEs).

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

CISA KEV — actively exploited

Affected technologies (1)

Cisco — Catalyst Sd-wan Manager

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2026-76504",
  "cveTags": [],
  "metrics": {
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        "ssvcData": {
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          "role": "CISA Coordinator",
          "options": [
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              "exploitation": "active"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-09-30T00:00:00+00:00"
        }
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    "cvssMetricV31": [
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          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
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        "exploitabilityScore": 3.9
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      "affectedData": [
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          "vendor": "Cisco",
          "product": "Cisco Catalyst SD-WAN Manager",
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              "version": "18.3.3"
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  "published": "2026-09-30T13:17:20.247",
  "references": [
    {
      "url": "https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-webauth-xr8beuuU",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ],
      "source": "psirt@cisco.com"
    },
    {
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-76504",
      "tags": [
        "US Government Resource"
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "psirt@cisco.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-177"
        }
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  "descriptions": [
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      "lang": "en",
      "value": "A vulnerability in the API session-based authentication management of Cisco Catalyst SD-WAN Manager could allow an unauthenticated, remote attacker to access an affected system with privileges of the admin user.\r\n\r\nThis vulnerability is due to improper handling of URI encoding in an HTTP request, which allows the request to bypass an authentication rule that is intended to restrict access to a specific API endpoint. An attacker could exploit this vulnerability by sending a crafted HTTP request to the API of the affected system. A successful exploit could allow the attacker to bypass authentication and gain access to the API as the admin user."
    }
  ],
  "lastModified": "2026-10-01T04:18:19.193",
  "cisaActionDue": "2026-10-03",
  "cisaExploitAdd": "2026-09-30",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:cisco:catalyst_sd-wan_manager:*:*:*:*:*:*:*:*",
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              "vulnerable": true,
              "matchCriteriaId": "A18803AF-4543-48CF-B285-491D299B9E4F",
              "versionEndExcluding": "20.15.6.1",
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              "criteria": "cpe:2.3:a:cisco:catalyst_sd-wan_manager:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "2C2E5FDB-3377-486E-A162-CC41CEDD6407",
              "versionEndExcluding": "20.18.4.1",
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          "operator": "OR"
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  "sourceIdentifier": "psirt@cisco.com",
  "cisaRequiredAction": "Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.",
  "cisaVulnerabilityName": "Cisco Catalyst SD-WAN Manager Hex Encoding Vulnerability"
}