{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "2.0.0"
              },
              {
                "fixed": "2.4.1"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "576997d3701306ccfa40b42e18b1bec5a6ac98a7"
            },
            {
              "fixed": "e6017b492b8ef55e24fd08dea45ce11780d7b4f7"
            }
          ],
          "repo": "https://github.com/ueberauth/guardian",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-9qx2-v587-q3gg"
  ],
  "database_specific": {
    "cna_assigner": "EEF",
    "cwe_ids": [
      "CWE-770"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55734.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "b7a6128ca4d0ffb7f7df5219dd982304ff9d6802"
          },
          {
            "fixed": "8d4efbfc352d30f5fcfc75a4d69a795b0e472724"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "Allocation of Resources Without Limits or Throttling vulnerability in ueberauth guardian (Guardian.Permissions module) allows a denial of service via BEAM atom-table exhaustion.\n\nThis vulnerability is associated with program file lib/guardian/permissions.ex and program routines 'Elixir.Guardian.Permissions':encode_permissions!/1, 'Elixir.Guardian.Permissions':encode_permissions_into_claims!/2, 'Elixir.Guardian.Permissions':do_encode_permissions!/2.\n\nThe Guardian.Permissions mixin installs a public encode_permissions!/1 function on every module that does use Guardian.Permissions. For each key of the supplied map, encode_permissions!/1 calls String.to_atom(to_string(k)) before any validation runs. The integer-value clause of do_encode_permissions!/2 then short-circuits straight to encoding without validating the key against the configured permission set, so a key with an integer value is interned as a fresh atom with no exception raised. Atoms are never garbage collected and the BEAM atom table is a fixed-size resource (default roughly 1,048,576 entries), so each unique attacker-chosen key permanently consumes one slot. An attacker who can influence a permission map that reaches encode_permissions!/1 (for example a permissions map read from a request body and passed into token issuance via encode_permissions_into_claims!/2) can mint an unbounded number of atoms and exhaust the atom table, crashing the entire BEAM node and every service running on it. The sibling decode_permissions/1 is not affected because it skips keys absent from the configured permission set.\n\nThis issue affects guardian: from 2.0.0 before 2.4.1.",
  "id": "CVE-2026-55734",
  "modified": "2026-08-04T11:31:10.347418588Z",
  "published": "2026-08-01T18:46:24.291Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-55734.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-55734"
    },
    {
      "type": "WEB",
      "url": "https://repo.hex.pm"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55734.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/ueberauth/guardian/security/advisories/GHSA-9qx2-v587-q3gg"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55734"
    },
    {
      "type": "FIX",
      "url": "https://github.com/ueberauth/guardian/commit/8d4efbfc352d30f5fcfc75a4d69a795b0e472724"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ueberauth/guardian"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H",
      "type": "CVSS_V4"
    }
  ],
  "summary": "guardian atom exhaustion in Guardian.Permissions.encode_permissions!/1"
}