{
  "affected": [
    {
      "database_specific": {
        "source": "https://cna.erlef.org/osv/EEF-CVE-2026-82761.json"
      },
      "package": {
        "ecosystem": "Hex",
        "name": "ash_authentication",
        "purl": "pkg:hex/ash_authentication"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.9.0"
            },
            {
              "fixed": "4.15.0"
            }
          ],
          "type": "SEMVER"
        },
        {
          "events": [
            {
              "introduced": "5.0.0-rc.0"
            },
            {
              "fixed": "5.0.0-rc.14"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": [
        "3.10.0",
        "3.10.1",
        "3.10.2",
        "3.10.3",
        "3.10.4",
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        "3.11.0",
        "3.11.1",
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        "3.11.11",
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        "3.9.6",
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        "4.0.0-rc.0",
        "4.0.0-rc.1",
        "4.0.0-rc.2",
        "4.0.0-rc.3",
        "4.0.0-rc.5",
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        "4.4.3",
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        "4.4.5",
        "4.4.6",
        "4.4.7",
        "4.4.8",
        "4.4.9",
        "4.5.0",
        "4.5.1",
        "4.5.2",
        "4.5.3",
        "4.5.4",
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        "4.6.0",
        "4.6.1",
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        "4.6.3",
        "4.6.4",
        "4.7.0",
        "4.7.1",
        "4.7.2",
        "4.7.3",
        "4.7.4",
        "4.7.5",
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        "4.8.0",
        "4.8.1",
        "4.8.2",
        "4.8.3",
        "4.8.5",
        "4.8.6",
        "4.8.7",
        "4.9.0",
        "4.9.1",
        "4.9.2",
        "4.9.3",
        "4.9.4",
        "4.9.5",
        "4.9.6",
        "4.9.7",
        "4.9.8",
        "4.9.9",
        "5.0.0-rc.0",
        "5.0.0-rc.1",
        "5.0.0-rc.10",
        "5.0.0-rc.11",
        "5.0.0-rc.12",
        "5.0.0-rc.13",
        "5.0.0-rc.2",
        "5.0.0-rc.3",
        "5.0.0-rc.4",
        "5.0.0-rc.5",
        "5.0.0-rc.6",
        "5.0.0-rc.7",
        "5.0.0-rc.8",
        "5.0.0-rc.9"
      ]
    },
    {
      "database_specific": {
        "source": "https://cna.erlef.org/osv/EEF-CVE-2026-82761.json"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "cf3d227ef25912cf1b0c5fa80f20001f5c46a102"
            },
            {
              "fixed": "18dfdb36c14aa6a61df8572bce2d5ec36b1d9840"
            },
            {
              "fixed": "9ef6864b8833d3b795427a7b8dc518a4997d41ab"
            }
          ],
          "repo": "https://github.com/team-alembic/ash_authentication",
          "type": "GIT"
        }
      ],
      "versions": [
        "v4.14.2",
        "v5.0.0-rc.13",
        "v4.14.1",
        "v5.0.0-rc.12",
        "v5.0.0-rc.11",
        "v5.0.0-rc.10",
        "v4.14.0",
        "v4.13.7",
        "5.0.0-rc.9",
        "5.0.0-rc.8",
        "v5.0.0-rc.7",
        "v5.0.0-rc.6",
        "v5.0.0-rc.5",
        "v5.0.0-rc.4",
        "v5.0.0-rc.3",
        "v5.0.0-rc.2",
        "v5.0.0-rc.1",
        "v5.0.0-rc.0",
        "v4.13.6",
        "v4.13.5",
        "v4.13.4",
        "v4.13.3",
        "v4.13.2",
        "v4.13.1",
        "v4.13.0",
        "v4.12.0",
        "v4.11.0",
        "v4.10.0",
        "v4.9.9",
        "v4.9.8",
        "v4.9.7",
        "v4.9.6",
        "v4.9.5",
        "v4.9.4",
        "v4.9.3",
        "v4.9.2",
        "v4.9.1",
        "v4.9.0",
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        "v4.8.5",
        "v4.8.4",
        "v4.8.3",
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        "v4.8.1",
        "v4.8.0",
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        "v4.7.3",
        "v4.7.2",
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        "v4.7.0",
        "v4.6.4",
        "v4.6.3",
        "v4.6.2",
        "v4.6.1",
        "v4.6.0",
        "v4.5.6",
        "v4.5.5",
        "v4.5.4",
        "v4.5.3",
        "v4.5.2",
        "v4.5.1",
        "v4.4.9",
        "v4.4.8",
        "v4.4.7",
        "v4.4.6",
        "v4.4.5",
        "v4.4.4",
        "v4.4.3",
        "v4.4.2",
        "v4.4.1",
        "v4.4.0",
        "v4.3.12",
        "v4.3.10",
        "v4.3.9",
        "v4.3.7",
        "v4.3.6",
        "v4.3.4",
        "v4.3.3",
        "v4.3.2",
        "v4.3.1",
        "v4.3.0",
        "v4.2.7",
        "v4.2.5",
        "v4.2.3",
        "v4.2.2",
        "v4.2.1",
        "v4.2.0",
        "v4.1.0",
        "v4.0.4",
        "v4.0.3",
        "v4.0.2",
        "v4.0.1",
        "v4.0.0",
        "v4.0.0-rc.7",
        "v4.0.0-rc.6",
        "v4.0.0-rc.5",
        "v4.0.0-rc.4",
        "v4.0.0-rc.3",
        "v4.0.0-rc.2",
        "v4.0.0-rc.1",
        "v4.0.0-rc.0",
        "v3.12.4",
        "v3.12.3",
        "v3.12.2",
        "v3.12.1",
        "v3.12.0",
        "v3.11.16",
        "v3.11.15",
        "v3.11.14",
        "v3.11.13",
        "v3.11.12",
        "v3.11.10",
        "v3.11.9",
        "v3.11.8",
        "v3.11.7",
        "v3.11.6",
        "v3.11.5",
        "v3.11.4",
        "v3.11.3",
        "v3.11.2",
        "v3.11.1",
        "v3.11.0",
        "v3.10.8",
        "v3.10.7",
        "v3.10.6",
        "v3.10.5",
        "v3.10.4",
        "v3.10.2",
        "v3.10.1",
        "v3.10.0",
        "v3.9.6",
        "v3.9.5",
        "v3.9.4",
        "v3.9.3",
        "v3.9.2",
        "v3.9.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-82761",
    "GHSA-23gr-vcp4-r27q"
  ],
  "credits": [
    {
      "name": "James Harton",
      "type": "REMEDIATION_DEVELOPER"
    },
    {
      "name": "Peter Ullrich",
      "type": "REPORTER"
    },
    {
      "name": "Jonatan Männchen / EEF",
      "type": "ANALYST"
    }
  ],
  "database_specific": {
    "capec_ids": [
      "CAPEC-29"
    ],
    "cpe_ids": [
      "cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*"
    ],
    "cwe_ids": [
      "CWE-367"
    ]
  },
  "details": "## Summary\n\nTime-of-check Time-of-use (TOCTOU) Race Condition vulnerability in team-alembic AshAuthentication allows an attacker holding a leaked magic link to replay its single-use token and authenticate as the target subject. A magic link configured with `single_use_token?`, which is the default, is meant to be redeemable exactly once, but nothing serialises the token's validity check against its consumption, so concurrent redemptions of one token all succeed and each yields a full user token.\n\nSign-in verifies the JWT with `Jwt.verify/4` and revokes it only afterwards: `AshAuthentication.Strategy.MagicLink.SignInPreparation` revokes in a `Query.after_action` callback, and `AshAuthentication.Strategy.MagicLink.SignInChange` in an `after_transaction` hook that runs once the sign-in has already committed. `AshAuthentication.TokenResource.Actions.revoke/3` writes the revocation as an upsert, so a concurrent duplicate revocation silently succeeds instead of conflicting and no request ever loses the race.\n\nThis issue affects ash_authentication: from 3.9.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.",
  "id": "EEF-CVE-2026-82761",
  "modified": "2026-09-17T13:26:03.671040166Z",
  "published": "2026-09-17T13:09:01.534Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-23gr-vcp4-r27q"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-82761.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com/team-alembic/ash_authentication/commit/cf3d227ef25912cf1b0c5fa80f20001f5c46a102"
    },
    {
      "type": "FIX",
      "url": "https://github.com/team-alembic/ash_authentication/commit/18dfdb36c14aa6a61df8572bce2d5ec36b1d9840"
    },
    {
      "type": "FIX",
      "url": "https://github.com/team-alembic/ash_authentication/commit/9ef6864b8833d3b795427a7b8dc518a4997d41ab"
    },
    {
      "type": "PACKAGE",
      "url": "https://hex.pm/packages/ash_authentication"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Magic link single-use tokens replayable via TOCTOU race in AshAuthentication"
}