FKIE_CVE-2026-4408

Vulnerability from fkie_nvd - Published: 2026-05-28 09:16 - Updated: 2026-06-17 10:56
Severity
9.0 (Critical) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
A flaw was found in Samba. A remote attacker can exploit a misconfiguration in Samba file servers and classic domain controllers that use the "check password script" feature. If this script is configured with the %u substitution character, the client-controlled username is passed without proper escaping of shell meta-characters. This vulnerability allows an attacker to achieve remote command execution on the affected system. This issue primarily affects non-standard configurations where the "check password script" is used with %u and the samba-dcerpcd service is started as a system service.
References
secalert@redhat.comhttps://access.redhat.com/errata/RHSA-2026:22644Issue Tracking
secalert@redhat.comhttps://access.redhat.com/errata/RHSA-2026:22963Issue Tracking
secalert@redhat.comhttps://access.redhat.com/errata/RHSA-2026:25049
secalert@redhat.comhttps://access.redhat.com/errata/RHSA-2026:25979
secalert@redhat.comhttps://access.redhat.com/security/cve/CVE-2026-4408Third Party Advisory
secalert@redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2479762Issue Tracking, Third Party Advisory
secalert@redhat.comhttps://bugzilla.samba.org/show_bug.cgi?id=16034Issue Tracking, Vendor Advisory
Impacted products
Vendor Product Version
redhat openshift_container_platform 4.0
samba samba *
redhat enterprise_linux 6.0
redhat enterprise_linux 7.0
redhat enterprise_linux 9.0
To clipboard 

{
  "affected": [
    {
      "affectedData": [
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          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:10.2"
          ],
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          "packageName": "samba",
          "product": "Red Hat Enterprise Linux 10",
          "vendor": "Red Hat",
          "versions": [
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              "status": "unaffected",
              "version": "0:4.23.5-109.el10_2",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
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            "cpe:/a:redhat:enterprise_linux:8::crb",
            "cpe:/o:redhat:enterprise_linux:8::baseos"
          ],
          "defaultStatus": "affected",
          "packageName": "samba",
          "product": "Red Hat Enterprise Linux 8",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "0:4.19.4-16.el8_10",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
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            "cpe:/o:redhat:enterprise_linux:8::baseos"
          ],
          "defaultStatus": "affected",
          "packageName": "samba",
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          "vendor": "Red Hat",
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              "status": "unaffected",
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              "versionType": "rpm"
            }
          ]
        },
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            "cpe:/a:redhat:enterprise_linux:9::crb",
            "cpe:/a:redhat:enterprise_linux:9::resilientstorage",
            "cpe:/o:redhat:enterprise_linux:9::baseos"
          ],
          "defaultStatus": "affected",
          "packageName": "samba",
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          "vendor": "Red Hat",
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              "status": "unaffected",
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              "versionType": "rpm"
            }
          ]
        },
        {
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          "cpes": [
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            "cpe:/a:redhat:enterprise_linux:9::crb",
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            "cpe:/o:redhat:enterprise_linux:9::baseos"
          ],
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          "vendor": "Red Hat",
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              "status": "unaffected",
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              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
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            "cpe:/a:redhat:rhel_eus:9.6::crb",
            "cpe:/a:redhat:rhel_eus:9.6::resilientstorage",
            "cpe:/o:redhat:rhel_eus:9.6::baseos"
          ],
          "defaultStatus": "affected",
          "packageName": "samba",
          "product": "Red Hat Enterprise Linux 9.6 Extended Update Support",
          "vendor": "Red Hat",
          "versions": [
            {
              "lessThan": "*",
              "status": "unaffected",
              "version": "0:4.21.3-14.el9_6.1",
              "versionType": "rpm"
            }
          ]
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:6"
          ],
          "defaultStatus": "unknown",
          "packageName": "samba",
          "product": "Red Hat Enterprise Linux 6",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
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          ],
          "defaultStatus": "unknown",
          "packageName": "samba4",
          "product": "Red Hat Enterprise Linux 6",
          "vendor": "Red Hat"
        },
        {
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          "cpes": [
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          ],
          "defaultStatus": "affected",
          "packageName": "samba",
          "product": "Red Hat Enterprise Linux 7",
          "vendor": "Red Hat"
        },
        {
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "cpes": [
            "cpe:/a:redhat:openshift:4"
          ],
          "defaultStatus": "affected",
          "packageName": "rhcos",
          "product": "Red Hat OpenShift Container Platform 4",
          "vendor": "Red Hat"
        }
      ],
      "source": "secalert@redhat.com"
    }
  ],
  "configurations": [
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              "matchCriteriaId": "932D137F-528B-4526-9A89-CD59FA1AB0FE",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:samba:samba:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "214F0165-932F-4289-BDC7-448402F05B3B",
              "versionEndExcluding": "4.21.0",
              "versionStartIncluding": "4.1.0",
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            },
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              "criteria": "cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "2F6AB192-9D7D-4A9A-8995-E53A9DE9EAFC",
              "vulnerable": true
            },
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              "criteria": "cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*",
              "matchCriteriaId": "142AD0DD-4CF3-4D74-9442-459CE3347E3A",
              "vulnerable": true
            },
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              "matchCriteriaId": "7F6FB57C-2BC7-487C-96DD-132683AEB35D",
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            }
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          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A flaw was found in Samba. A remote attacker can exploit a misconfiguration in Samba file servers and classic domain controllers that use the \"check password script\" feature. If this script is configured with the %u substitution character, the client-controlled username is passed without proper escaping of shell meta-characters. This vulnerability allows an attacker to achieve remote command execution on the affected system. This issue primarily affects non-standard configurations where the \"check password script\" is used with %u and the samba-dcerpcd service is started as a system service."
    }
  ],
  "id": "CVE-2026-4408",
  "lastModified": "2026-06-17T10:56:32.163",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.0,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H",
          "version": "3.1"
        },
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        "impactScore": 6.0,
        "source": "secalert@redhat.com",
        "type": "Secondary"
      },
      {
        "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"
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        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
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        "ssvcData": {
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          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-05-29T03:55:49.995145Z",
          "version": "2.0.3"
        }
      }
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  },
  "published": "2026-05-28T09:16:47.643",
  "references": [
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      "source": "secalert@redhat.com",
      "tags": [
        "Issue Tracking"
      ],
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    },
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      "tags": [
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      "tags": [
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      "tags": [
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  "sourceIdentifier": "secalert@redhat.com",
  "vulnStatus": "Modified",
  "weaknesses": [
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      "description": [
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          "lang": "en",
          "value": "CWE-78"
        }
      ],
      "source": "secalert@redhat.com",
      "type": "Secondary"
    }
  ]
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.