FKIE_CVE-2026-102631

Vulnerability from fkie_nvd - Published: 2026-10-15 17:17 - Updated: 2026-10-16 21:17
Severity
5.9 (Medium) - CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
Summary
In authd before 0.7.1, the user identity matching in UpdateUser (internal/users/manager.go) resolves an incoming login by the broker-scoped provider ID, but falls back to matching the username when the provider ID does not belong to any known user, and does not reject a conflicting non-empty provider ID. If an identity provider reassigns an email address, which authd uses as the username, to a new account, the new account inherits the previous user's local UID and home directory on its next login. This allows the new user to access and modify files belonging to the previous user, including credentials such as SSH keys and cloud API tokens, and silently rebinds the local account record to the new identity. As a mitigation, administrators should lock or delete the previous user's local authd account when the corresponding IdP account is removed.
References
security@ubuntu.comhttps://bugs.launchpad.net/ubuntu/+source/authd/+bug/2168531
security@ubuntu.comhttps://github.com/canonical/authd/pull/2067
security@ubuntu.comhttps://ubuntu.com/security/CVE-2026-102631
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "packageName": "authd",
          "platforms": [
            "Linux"
          ],
          "product": "authd",
          "repo": "https://github.com/canonical/authd",
          "vendor": "Canonical",
          "versions": [
            {
              "lessThan": "0.7.1",
              "status": "affected",
              "version": "0.1",
              "versionType": "custom"
            },
            {
              "lessThan": "0.7.1~ubuntu24.04.1",
              "status": "affected",
              "version": "0.1",
              "versionType": "custom"
            },
            {
              "lessThan": "0.7.1~ubuntu26.04",
              "status": "affected",
              "version": "0.1",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "security@ubuntu.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In authd before 0.7.1, the user identity matching in UpdateUser (internal/users/manager.go) resolves an incoming login by the broker-scoped provider ID, but falls back to matching the username when the provider ID does not belong to any known user, and does not reject a conflicting non-empty provider ID. If an identity provider reassigns an email address, which authd uses as the username, to a new account, the new account inherits the previous user\u0027s local UID and home directory on its next login. This allows the new user to access and modify files belonging to the previous user, including credentials such as SSH keys and cloud API tokens, and silently rebinds the local account record to the new identity. As a mitigation, administrators should lock or delete the previous user\u0027s local authd account when the corresponding IdP account is removed."
    }
  ],
  "id": "CVE-2026-102631",
  "lastModified": "2026-10-16T21:17:11.620",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "HIGH",
          "attackRequirements": "PRESENT",
          "attackVector": "LOCAL",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 5.9,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security@ubuntu.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-102631",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-16T20:16:37.623815Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-10-15T17:17:10.130",
  "references": [
    {
      "source": "security@ubuntu.com",
      "url": "https://bugs.launchpad.net/ubuntu/+source/authd/+bug/2168531"
    },
    {
      "source": "security@ubuntu.com",
      "url": "https://github.com/canonical/authd/pull/2067"
    },
    {
      "source": "security@ubuntu.com",
      "url": "https://ubuntu.com/security/CVE-2026-102631"
    }
  ],
  "sourceIdentifier": "security@ubuntu.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-287"
        }
      ],
      "source": "security@ubuntu.com",
      "type": "Secondary"
    }
  ]
}



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