{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.0.0"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "eml_parser"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44844"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-674"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-08T23:12:51Z",
    "nvd_published_at": "2026-05-26T21:16:39Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\n`EmlParser.get_raw_body_text()` recurses unconditionally for every nested `message/rfc822` attachment without any depth limit. An attacker who can supply a badly crafted EML file with approximately 120 nested `message/rfc822` parts triggers an unhandled `RecursionError` and aborts parsing of the message. A 12 KB EML file is enough to crash a worker.\nThough this causes the parser to crash, it is an unlikely scenario as the suggested EML that crashes the parser would not pass basic RFC compliance tests.\n\n### Details\n\nThe vulnerable function is `EmlParser.get_raw_body_text()` in `eml_parser/parser.py`. For every part of type `multipart/*`, the function iterates over its sub-parts; for every sub-part of type `message/rfc822`, it calls itself recursively on the inner message:\n\nThere is no depth parameter and no early-abort. CPython\u0027s default `sys.recursionlimit` is 1000. Each level of `message/rfc822` nesting adds approximately 8 frames to the stack (parser code + stdlib `_header_value_parser` calls), so roughly 120 nested levels exhaust the limit.\n\nThe `RecursionError` is not caught anywhere along the call chain, so it propagates out of `decode_email_bytes()` and aborts processing of the entire message.\n\n\n### PoC\n\nEnvironment: Python 3.12.3, eml_parser 3.0.0 (`pip install eml_parser==3.0.0`), default `sys.recursionlimit=1000`, Ubuntu 24.04 aarch64. No special configuration of `EmlParser`, default constructor.\n\nSelf-contained reproducer that builds the PoC and triggers the crash:\n\n```python\nimport eml_parser\n\ndef build_poc(depth=124):\n    inner = b\"From: a@a\\r\\nTo: b@b\\r\\nContent-Type: text/plain\\r\\n\\r\\n.\\r\\n\"\n    msg = inner\n    for i in range(depth):\n        b = f\"B{i}\".encode()\n        msg = (\n            b\u0027Content-Type: multipart/mixed; boundary=\"\u0027 + b + b\u0027\"\\r\\n\\r\\n\u0027\n            b\u0027--\u0027 + b + b\u0027\\r\\nContent-Type: message/rfc822\\r\\n\\r\\n\u0027\n        ) + msg + b\u0027\\r\\n--\u0027 + b + b\u0027--\\r\\n\u0027\n    return msg\n\nep = eml_parser.EmlParser()\nep.decode_email_bytes(build_poc())\n# RecursionError after ~76 ms on Apple Silicon (Ubuntu 24.04 aarch64).\n```\n\nNote that the suggested code does not produce an RFC compliant message.\nResulting EML payload size: 12,369 bytes.\nSHA-256 of generated PoC: `00f15f635e21b4144967c2893b37425e6a6bd7b4185c557e5c7e904e1e6d18e8`\n\nThe crash is deterministic on a stock install. No network, no special headers, no large attachments.\n\n### Impact\n\nDenial of service of any pipeline that processes attacker-supplied EML files using `eml_parser`.\n\nA single 12 KB email is enough to crash a worker. If the worker is a long-running process triaging multiple emails, the unhandled exception aborts processing of the whole batch unless the caller wraps the call in a broad `try/except`. Even then, attacker-supplied volume can keep workers in a perpetual restart loop.\n\nThe vulnerability is exploitable pre-authentication in any deployment that ingests emails from external senders which have not been subject to any kind of basic validation.\nConsidering that email messages pass through a mail-server which does some kind of validation, messages as produced by the  *build_poc* function would not reach eml_parser.\nNonetheless recursion depth checks have been implemented to handle the described issue.\n\n\n### Reporter\n\nSebasti\u00e1n Alba Vives (`@Sebasteuo`)\nIndependent security researcher, Senior AppSec Consultant\nLinkedIn: https://www.linkedin.com/in/sebastian-alba\nEmail: sebasjosue84@gmail.com\nPGP: `0D1A E4C2 CFC8 894F 19EA  DA24 45CD CA33 2CF8 31F4`",
  "id": "GHSA-g47v-rwmh-r9f8",
  "modified": "2026-06-08T23:30:15Z",
  "published": "2026-05-08T23:12:51Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/GOVCERT-LU/eml_parser/security/advisories/GHSA-g47v-rwmh-r9f8"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44844"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/GOVCERT-LU/eml_parser"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "eml_parser has recursion DoS via nested message/rfc822 attachments"
}