{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.2.0"
              },
              {
                "fixed": "4.15.0"
              },
              {
                "introduced": "5.0.0-rc.0"
              },
              {
                "fixed": "5.0.0-rc.14"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "809a0faa55fc29fe08c6586fb53643605b09d2a3"
            },
            {
              "fixed": "d6b2be35cf8f0b8ab84e7a934cfb0d91de0a3c17"
            },
            {
              "introduced": "6767fe27eb952e5bc09aa2e5a7d8f96f5a1c424a"
            },
            {
              "fixed": "fea75958a081ed337ceb578396174039694c48df"
            },
            {
              "fixed": "3e1d452cbf1564e87f5f97be882b66fe25af7cfa"
            },
            {
              "fixed": "872db454405ecad4fcdabd9ff3d8755d1d6a69ae"
            },
            {
              "fixed": "a939dde9b917c072cdf10c4b0913a9886a4b0231"
            }
          ],
          "repo": "https://github.com/team-alembic/ash_authentication",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-v577-944g-7h3x"
  ],
  "database_specific": {
    "cna_assigner": "EEF",
    "cwe_ids": [
      "CWE-384"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86688.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "a939dde9b917c072cdf10c4b0913a9886a4b0231"
          },
          {
            "fixed": "*"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "Session Fixation vulnerability in team-alembic ash_authentication allows an attacker who can plant a session identifier in a victim's browser to hold an authenticated session once that victim signs in.\n\nAshAuthentication.Plug.Helpers.store_in_session/2 writes the authenticated subject into the existing session with Plug.Conn.put_session/3 and never calls Plug.Conn.configure_session(renew: true), so the identifier the visitor arrived with carries into their authenticated session. Every authentication event reaches this one function: the default success/4 injected by AshAuthentication.Phoenix.Controller.__using__/1, the AuthController emitted by mix ash_authentication_phoenix.install, and remember-me auto-login. AshAuthentication.Phoenix.Plug.store_in_session/2 is a defdelegate to it. Logout does not close the window either, because clear_session/2 ends with Plug.Conn.clear_session/1, which clears session contents but leaves the identifier intact, so a planted identifier survives a logout-then-login cycle.\n\nThis issue affects ash_authentication: from 0.2.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.",
  "id": "CVE-2026-86688",
  "modified": "2026-09-20T11:30:32.536839424Z",
  "published": "2026-09-17T21:58:00.853Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-86688.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-86688"
    },
    {
      "type": "WEB",
      "url": "https://repo.hex.pm"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86688.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-v577-944g-7h3x"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-86688"
    },
    {
      "type": "FIX",
      "url": "https://github.com/team-alembic/ash_authentication/commit/3e1d452cbf1564e87f5f97be882b66fe25af7cfa"
    },
    {
      "type": "FIX",
      "url": "https://github.com/team-alembic/ash_authentication/commit/872db454405ecad4fcdabd9ff3d8755d1d6a69ae"
    },
    {
      "type": "FIX",
      "url": "https://github.com/team-alembic/ash_authentication/commit/a939dde9b917c072cdf10c4b0913a9886a4b0231"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/team-alembic/ash_authentication"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Session id is not renewed on authentication in ash_authentication, allowing session fixation"
}