CVE-2026-58393

Status: DeferredMedium (5.9)—

Severity5.9Medium · CVSS 3.1

Exploitation probability0.43 %higher than 36% of CVEs

Active exploitationNonot in the CISA catalog

Public exploitNot knownno public code found

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the OpenVPN Client Specific Override common_name field accepts path traversal sequences and openvpn_csc_conf_write() concatenates the value into /var/etc/openvpn-csc/<vpnid>/<common_name> without normalization or a basename check. The affected event handlers are client_connect.php and user_pass_verify.php.

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An authenticated user with Client Specific Override privileges can store the traversal value, and a matching OpenVPN client-connect or authentication event causes a generated CSO file to be written outside the intended directory. The file content is generated OpenVPN configuration rather than arbitrary bytes, and practical exploitation requires the attacker to cause a matching common name or username to be processed. This issue is fixed in version 26.1.11.

CVSS

Base score: 5.9
Version: 3.1
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.43 %
Percentile among all scored CVEs: 36
Score date: 10/20/2026

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).

ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1210 Exploitation of Remote Serviceslateral movement85 %
Primary impactT1565.001 Stored Data Manipulationimpact55 %

Vector AV:N con PR:L (privilegios requeridos) indica T1210; el texto describe escritura de ficheros CSO fuera del directorio previsto, lo que sugiere manipulación de datos almacenados.

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

ATT&CK mitigations that cover these techniques

Vulnerability Scanning Threat Intelligence Program Restrict File and Directory Permissions Privileged Account Management Remote Data Storage Network Segmentation

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Opnsense — Opnsense^AI

CWEs

CWE-22

References

Show 4 references

Raw JSON (NVD)

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{
  "id": "CVE-2026-58393",
  "cveTags": [],
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          "role": "CISA Coordinator",
          "options": [
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            {
              "automatable": "no"
            },
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              "technicalImpact": "partial"
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          "version": "2.0.3",
          "timestamp": "2026-10-15T16:07:43.427308Z"
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          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "HIGH",
          "availabilityImpact": "LOW",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
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        "exploitabilityScore": 1.6
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      "affectedData": [
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  "published": "2026-10-15T16:18:18.310",
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      "url": "https://github.com/opnsense/core/commit/3af496143a19153c18b2f9458b2510d58aff2b98",
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  "descriptions": [
    {
      "lang": "en",
      "value": "OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the OpenVPN Client Specific Override common_name field accepts path traversal sequences and openvpn_csc_conf_write() concatenates the value into /var/etc/openvpn-csc/<vpnid>/<common_name> without normalization or a basename check. The affected event handlers are client_connect.php and user_pass_verify.php. An authenticated user with Client Specific Override privileges can store the traversal value, and a matching OpenVPN client-connect or authentication event causes a generated CSO file to be written outside the intended directory. The file content is generated OpenVPN configuration rather than arbitrary bytes, and practical exploitation requires the attacker to cause a matching common name or username to be processed. This issue is fixed in version 26.1.11."
    }
  ],
  "lastModified": "2026-10-15T21:08:49.703",
  "sourceIdentifier": "security-advisories@github.com"
}