FKIE_CVE-2026-117656

Vulnerability from fkie_nvd - Published: 2026-10-31 00:16 - Updated: 2026-10-31 00:16
Severity
9.3 (Critical) - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Summary
Acceptance of Extraneous Untrusted Data With Trusted Data vulnerability in the Sign in with Apple strategy in pow-auth Assent allows an unauthenticated remote attacker to impersonate another user via the user parameter of the authorization callback. Apple posts the user's name to the callback endpoint in a user form parameter that the browser submits and the client controls. Assent.Strategy.Apple.callback/2 in lib/assent/strategies/apple.ex decodes that parameter, and fetch_user/2 merges it over the claims of the verified ID token, so the unverified map wins. An attacker who completes a Sign in with Apple login with their own Apple ID and edits the user parameter can replace sub, email, and any other claim. Applications that look up, link, or authorize accounts by the returned subject or email then act on the attacker's values. This issue affects assent: from 0.1.25 before 0.3.2.
References
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://cna.erlef.org/cves/CVE-2026-117656.html
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/pow-auth/assent/commit/18898bde0296152165ae470078490e5798329b1b
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/pow-auth/assent/commit/a2d331e8c51376d6c0b04a81aad31e0b4d4d64a3
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://github.com/pow-auth/assent/security/advisories/GHSA-9fr5-g44g-9526
6b3ad84c-e1a6-4bf7-a703-f496b71e49dbhttps://osv.dev/vulnerability/EEF-CVE-2026-117656
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:pow-auth:assent:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "\u0027Elixir.Assent.Strategy.Apple\u0027"
          ],
          "packageName": "assent",
          "packageURL": "pkg:hex/assent",
          "product": "assent",
          "programFiles": [
            "lib/assent/strategies/apple.ex"
          ],
          "programRoutines": [
            {
              "name": "\u0027Elixir.Assent.Strategy.Apple\u0027:callback/2"
            },
            {
              "name": "\u0027Elixir.Assent.Strategy.Apple\u0027:fetch_user/2"
            }
          ],
          "repo": "https://github.com/pow-auth/assent",
          "vendor": "pow-auth",
          "versions": [
            {
              "lessThan": "0.3.2",
              "status": "affected",
              "version": "0.1.25",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:pow-auth:assent:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "\u0027Elixir.Assent.Strategy.Apple\u0027"
          ],
          "packageName": "pow-auth/assent",
          "packageURL": "pkg:github/pow-auth/assent",
          "product": "assent",
          "programFiles": [
            "lib/assent/strategies/apple.ex"
          ],
          "programRoutines": [
            {
              "name": "\u0027Elixir.Assent.Strategy.Apple\u0027:callback/2"
            },
            {
              "name": "\u0027Elixir.Assent.Strategy.Apple\u0027:fetch_user/2"
            }
          ],
          "repo": "https://github.com/pow-auth/assent",
          "vendor": "pow-auth",
          "versions": [
            {
              "lessThan": "18898bde0296152165ae470078490e5798329b1b",
              "status": "affected",
              "version": "a2d331e8c51376d6c0b04a81aad31e0b4d4d64a3",
              "versionType": "git"
            }
          ]
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Acceptance of Extraneous Untrusted Data With Trusted Data vulnerability in the Sign in with Apple strategy in pow-auth Assent allows an unauthenticated remote attacker to impersonate another user via the user parameter of the authorization callback.\n\nApple posts the user\u0027s name to the callback endpoint in a user form parameter that the browser submits and the client controls. Assent.Strategy.Apple.callback/2 in lib/assent/strategies/apple.ex decodes that parameter, and fetch_user/2 merges it over the claims of the verified ID token, so the unverified map wins. An attacker who completes a Sign in with Apple login with their own Apple ID and edits the user parameter can replace sub, email, and any other claim. Applications that look up, link, or authorize accounts by the returned subject or email then act on the attacker\u0027s values.\n\nThis issue affects assent: from 0.1.25 before 0.3.2."
    }
  ],
  "id": "CVE-2026-117656",
  "lastModified": "2026-10-31T00:16:51.340",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 9.3,
          "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:N/PR:N/UI:N/VC:H/VI:H/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": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-10-31T00:16:51.340",
  "references": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://cna.erlef.org/cves/CVE-2026-117656.html"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/pow-auth/assent/commit/18898bde0296152165ae470078490e5798329b1b"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/pow-auth/assent/commit/a2d331e8c51376d6c0b04a81aad31e0b4d4d64a3"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/pow-auth/assent/security/advisories/GHSA-9fr5-g44g-9526"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-117656"
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-290"
        },
        {
          "lang": "en",
          "value": "CWE-349"
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary"
    }
  ]
}



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