FKIE_CVE-2026-49757

Vulnerability from fkie_nvd - Published: 2026-06-15 12:16 - Updated: 2026-06-15 20:55
Severity
9.2 (Critical) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Summary
Authentication Bypass by Spoofing vulnerability in team-alembic AshAuthentication allows account takeover of local users via OAuth2/OIDC sign-in. AshAuthentication's OAuth2 and OIDC family strategies matched the local user by email address (an upsert on the email field, or a user-defined sign-in filter) rather than by the OpenID Connect iss/sub claim combination. Per OpenID Connect Core §5.7, only iss/sub uniquely and stably identifies an end-user; other claims, including email, MUST NOT be used as unique identifiers. A provider login presenting a victim's email, including an unverified email, a reused email, or an account with email_verified: false, resolved to and signed in as the victim's existing local account. An unauthenticated attacker who can register an account on any accepted OAuth provider with the victim's email (or who benefits from provider-side email reuse or reclamation) obtains the victim's full local privileges. The fix resolves users by the (strategy, sub) identity stored in a user identity resource, and only links a new sub to an existing local account by email when the provider's email_verified claim is trusted (trust_email_verified?). This issue affects ash_authentication from 0.1.0 before 4.14.0 and from 5.0.0-rc.0 before 5.0.0-rc.10.
References
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://cna.erlef.org/cves/CVE-2026-49757.html
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/team-alembic/ash_authentication/commit/64530644f9b37ebb76ca14aeb83a77597a0034b7
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/team-alembic/ash_authentication/commit/728b8d28c1b5f465fa1116ef044a815300fc733d
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/team-alembic/ash_authentication/security/advisories/GHSA-777c-2fxx-qr28
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://osv.dev/vulnerability/EEF-CVE-2026-49757
Impacted products
Vendor Product Version
To clipboard 

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Authentication Bypass by Spoofing vulnerability in team-alembic AshAuthentication allows account takeover of local users via OAuth2/OIDC sign-in.\n\nAshAuthentication\u0027s OAuth2 and OIDC family strategies matched the local user by email address (an upsert on the email field, or a user-defined sign-in filter) rather than by the OpenID Connect iss/sub claim combination. Per OpenID Connect Core \u00a75.7, only iss/sub uniquely and stably identifies an end-user; other claims, including email, MUST NOT be used as unique identifiers.\n\nA provider login presenting a victim\u0027s email, including an unverified email, a reused email, or an account with email_verified: false, resolved to and signed in as the victim\u0027s existing local account. An unauthenticated attacker who can register an account on any accepted OAuth provider with the victim\u0027s email (or who benefits from provider-side email reuse or reclamation) obtains the victim\u0027s full local privileges.\n\nThe fix resolves users by the (strategy, sub) identity stored in a user identity resource, and only links a new sub to an existing local account by email when the provider\u0027s email_verified claim is trusted (trust_email_verified?).\n\nThis issue affects ash_authentication from 0.1.0 before 4.14.0 and from 5.0.0-rc.0 before 5.0.0-rc.10."
    }
  ],
  "id": "CVE-2026-49757",
  "lastModified": "2026-06-15T20:55:48.070",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 9.2,
          "baseSeverity": "CRITICAL",
          "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:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/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": "HIGH",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-06-15T12:16:25.777",
  "references": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://cna.erlef.org/cves/CVE-2026-49757.html"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/team-alembic/ash_authentication/commit/64530644f9b37ebb76ca14aeb83a77597a0034b7"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/team-alembic/ash_authentication/commit/728b8d28c1b5f465fa1116ef044a815300fc733d"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-777c-2fxx-qr28"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-49757"
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-290"
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary"
    }
  ]
}


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