Unbounded atom creation from unsigned LogoutResponse status codes in esaml allows atom table exhaustion

{
  "id": "6aacd10c787e40e59f6ea66390b045a9fd0a433a8cd7eba14008008cc7555cee",
  "url": "https://osv.dev/vulnerability/EEF-CVE-2026-86696",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Unbounded atom creation from unsigned LogoutResponse status codes in esaml allows atom table exhaustion",
    "summary": "## Summary Allocation of Resources Without Limits or Throttling vulnerability in `esaml` in dropbox esaml allows an unauthenticated attacker to exhaust the Erlang VM atom table and crash the node via unsigned `LogoutResponse` messages. `esaml:status_code_map/1` in `src/esaml.erl` maps any `StatusCode` value it does not recognize to an atom with `list_to_atom/1` on the last colon-separated segment of the URN. `esaml_sp:validate_logout_response/2` verifies a signature only when the message carries one, so an unsigned `LogoutResponse` posted to the single-logout endpoint reaches `esaml:decode_logout_response/1` and mints one permanent atom per distinct status value. Atoms are never reclaimed and the VM caps the atom table at about one million entries, so an attacker who posts that many distinct values aborts the node. This issue affects esaml: from 0.1.0 onward. ## Details **1. Input.** The single-logout endpoint in `esaml_cowboy:validate_logout/2` reads the request body, decodes the `SAMLResponse` form field with `esaml_binding:decode_response/2`, and passes a `samlp:LogoutResponse` document to `esaml_sp:validate_logout_response/2`. **2. No signature required.** `validate_logout_response/2` looks for a `ds:Signature` element and verifies it only when one is present. An unsigned document passes through unchanged to `esaml:decode_logout_response/1`, which requires only the `Version` and `IssueInstant` attributes before mapping the `StatusCode` value. **3. Interning.** `esaml:stat",
    "evidence": "osv:EEF-CVE-2026-86696",
    "products": [
      {
        "name": {
          "value": "esaml",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "3.0.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.1.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.2.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.3.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.4.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.5.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.6.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.6.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.7.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "4.0.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "4.1.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "4.2.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "4.3.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "4.4.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "4.5.0",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "4.6.0",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "EEF-CVE-2026-86696",
      "aliases": [
        "CVE-2026-86696",
        "EEF-CVE-2026-86696"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.1.0"
                }
              ]
            }
          ],
          "package": {
            "name": "esaml",
            "purl": "pkg:hex/esaml",
            "ecosystem": "Hex"
          },
          "versions": [
            "3.0.1",
            "3.1.0",
            "3.2.0",
            "3.3.0",
            "3.4.0",
            "3.5.0",
            "3.6.0",
            "3.6.1",
            "3.7.0",
            "4.0.0",
            "4.1.0",
            "4.2.0",
            "4.3.0",
            "4.4.0",
            "4.5.0",
            "4.6.0"
          ],
          "database_specific": {
            "source": "https://cna.erlef.org/osv/EEF-CVE-2026-86696.json"
          }
        },
        {
          "ranges": [
            {
              "repo": "https://github.com/handnot2/esaml",
              "type": "GIT",
              "events": [
                {
                  "introduced": "be692b56245071899757afa7ef47e43593d3de96"
                }
              ]
            }
          ],
          "versions": [
            "v4.2.0",
            "v3.6.1",
            "v4.1.0",
            "v4.0.0",
            "v3.6.0",
            "v3.5.0",
            "v3.4.0",
            "v3.3.0",
            "v3.2.0",
            "v3.1.0",
            "v3.0.1",
            "v3.0.0",
            "v2.1.0",
            "2.0.0",
            "v1.1",
            "v1.0"
          ],
          "database_specific": {
            "source": "https://cna.erlef.org/osv/EEF-CVE-2026-86696.json"
          }
        },
        {
          "ranges": [
            {
              "repo": "https://github.com/arekinath/esaml",
              "type": "GIT",
              "events": [
                {
                  "introduced": "be692b56245071899757afa7ef47e43593d3de96"
                }
              ]
            }
          ],
          "versions": [
            "v1.1",
            "v1.0"
          ],
          "database_specific": {
            "source": "https://cna.erlef.org/osv/EEF-CVE-2026-86696.json"
          }
        },
        {
          "ranges": [
            {
              "repo": "https://github.com/dropbox/esaml",
              "type": "GIT",
              "events": [
                {
                  "introduced": "be692b56245071899757afa7ef47e43593d3de96"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://cna.erlef.org/osv/EEF-CVE-2026-86696.json"
          }
        }
      ],
      "modified": "2026-10-22T07:00:03.393933843Z",
      "provider": "osv",
      "references": [
        "https://cna.erlef.org/cves/CVE-2026-86696.html",
        "https://github.com/handnot2/esaml/commit/be692b56245071899757afa7ef47e43593d3de96",
        "https://github.com/arekinath/esaml/commit/be692b56245071899757afa7ef47e43593d3de96",
        "https://github.com/dropbox/esaml/commit/be692b56245071899757afa7ef47e43593d3de96",
        "https://hex.pm/packages/esaml"
      ],
      "provider_metadata": {
        "cpe_ids": [
          "cpe:2.3:a:handnot2:esaml:*:*:*:*:*:*:*:*",
          "cpe:2.3:a:arekinath:esaml:*:*:*:*:*:*:*:*",
          "cpe:2.3:a:dropbox:esaml:*:*:*:*:*:*:*:*"
        ],
        "cwe_ids": [
          "CWE-770"
        ],
        "capec_ids": [
          "CAPEC-125"
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-86696",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 404580,
  "published_at": "2026-10-22T06:59:07.68+00:00"
}