CWE-1124

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          "value": "eml_parser serves as a python module for parsing eml files and returning various information found in the e-mail as well as computed information. Prior to 3.0.2, eml_parser.routing.noparenthesis in eml_parser/routing.py removes parenthesized CFWS comments from Received: headers with a regex-based fix-point loop whose running time is quadratic in the nesting depth. A single Received: header with 5,000 nested parentheses causes approximately 1.3 seconds of CPU saturation per parsed message, and doubling the nesting depth approximately quadruples the running time. An attacker can submit relatively small EML files that consume multiple seconds of processing time, causing worker latency, queue backpressure, and possible service-level outages in synchronous gateways, sandboxes, and real-time triage pipelines. This issue is fixed in version 3.0.2."
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      "title": "eml_parser: DoS via deeply nested parens in Received headers"
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          "value": "eml_parser serves as a python module for parsing eml files and returning various information found in the e-mail as well as computed information. Prior to 3.0.2, eml_parser.parser.HeaderParser.header_fetch_parse in eml_parser/parser.py uses email.utils.getaddresses() to parse address-bearing e-mail headers. A deeply nested CFWS comment construct exhausts the standard-library recursive descent parser\u0027s call stack and raises RecursionError, which is not caught and therefore aborts parsing of the entire message. An attacker can disrupt SOC pipelines that process untrusted EML files, although callers already need to handle exceptions from malformed or pathological messages. This issue is fixed in version 3.0.2."
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      "title": "eml_parser: Parser DoS via deeply nested parentheses in e-mail headers"
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{
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    {
      "package": {
        "ecosystem": "PyPI",
        "name": "eml_parser"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
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  "aliases": [
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    "cwe_ids": [
      "CWE-770",
      "CWE-1124"
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    "github_reviewed": true,
    "github_reviewed_at": "2026-08-25T18:27:18Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\n`eml_parser` strips parenthesised CFWS comments from `Received:` headers using a regex-based fix-point loop. The loop has quadratic time complexity in the number of nested parens. A single `Received:` header containing 5,000 nested parens causes ~1.3 seconds of CPU saturation per parsed message; runtime quadruples per doubling of nesting depth.\n\n### Impact\n\nThis represents a CPU exhaustion DoS in any pipeline that processes attacker-supplied EML files. An attacker can create relatively small EML files that will take multiple seconds to parse.\n\nThis is particularly problematic for synchronous email-processing pipelines (gateways, sandboxes, real-time triage) where worker latency directly translates to queue backpressure and possible service-level outages.\n\n### Patches\n\nSince version 3.0.2, `eml_parser` uses a linear-time algorithm to remove the comments from `Received:` headers.",
  "id": "GHSA-g7gc-gmgp-wgqg",
  "modified": "2026-08-25T18:27:18Z",
  "published": "2026-08-25T18:27:18Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/GOVCERT-LU/eml_parser/security/advisories/GHSA-g7gc-gmgp-wgqg"
    },
    {
      "type": "WEB",
      "url": "https://github.com/GOVCERT-LU/eml_parser/pull/90"
    },
    {
      "type": "WEB",
      "url": "https://github.com/GOVCERT-LU/eml_parser/commit/746a69f86443eb0b6a47f77db3cfe727c21f92b3"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/GOVCERT-LU/eml_parser"
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    {
      "type": "WEB",
      "url": "https://github.com/GOVCERT-LU/eml_parser/releases/tag/v3.0.2"
    }
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  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "eml_parser vulnerable to DoS via deeply nested parens in Received headers"
}

{
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        "ecosystem": "PyPI",
        "name": "eml_parser"
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        {
          "events": [
            {
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            {
              "fixed": "3.0.2"
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          "type": "ECOSYSTEM"
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  "aliases": [
    "CVE-2026-55619"
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    "cwe_ids": [
      "CWE-1124",
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-25T18:25:47Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "### Summary\n\n`eml_parser` uses the `email.utils.getaddresses()` function from the CPython standard library to parse e-mail headers that contain e-mail addresses (such as `To`, `Cc`, `Bcc`, `From`, `Reply-To`, `Sender`, ...). When the input header contains a deeply nested CFWS (comment / folding white space) construct, the recursive descent parser in the standard library exhausts the call stack. The resulting `RecursionError` is not caught by `eml_parser`, so the exception propagates and aborts parsing of the whole message.\n\n### Impact\n\nSOC pipelines use `eml_parser` to process untrusted e-mails. An attacker can easily create an eml file that will trigger the `RecursionError` during parsing.\n\nThe impact is mitigated by the fact that there are various other situations in which `eml_parser` will raise an exception when attempting to parse a malformed or pathological eml file. In particular, very deeply nested multipart e-mails also result in a `RecursionError` being raised by the library voluntarily. Therefore, systems relying on `eml_parser` already need to detect and handle errors emanating from the library in an appropriate way.\n\n### Workarounds\n\nThe issue can be avoided by wrapping the call to `eml_parser.decode_email` or `eml_parser.decode_email_bytes` in a `try/except` construct.\n\n### Patches\n\nSince version 3.0.2, `eml_parser` will catch the error in the standard library parser and fall back to a simpler parser based on a regular expression.",
  "id": "GHSA-m66c-fw79-6359",
  "modified": "2026-08-25T18:25:47Z",
  "published": "2026-08-25T18:25:47Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/GOVCERT-LU/eml_parser/security/advisories/GHSA-m66c-fw79-6359"
    },
    {
      "type": "WEB",
      "url": "https://github.com/GOVCERT-LU/eml_parser/pull/90"
    },
    {
      "type": "WEB",
      "url": "https://github.com/GOVCERT-LU/eml_parser/commit/746a69f86443eb0b6a47f77db3cfe727c21f92b3"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/GOVCERT-LU/eml_parser"
    },
    {
      "type": "WEB",
      "url": "https://github.com/GOVCERT-LU/eml_parser/releases/tag/v3.0.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "eml_parser has parser DoS via deeply nested parentheses in e-mail headers"
}