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GHSA-HM9V-VJ3R-R55M

Vulnerability from github – Published: 2023-06-30 22:19 – Updated: 2023-06-30 22:19
VLAI
Summary
PyPDF2 vulnerable to possible Infinite Loop when reading malformed objects
Details

Impact

An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF.

Patches

The issue was fixed with https://github.com/py-pdf/pypdf/pull/1331

Workarounds

If you cannot update your version of PyPDF2 (preferably to pypdf>3.1.0 as PyPDF2 is deprecated), you should modify PyPDF2/generic/_data_structures.py::read_object.

Replace:

    else:
        # number object OR indirect reference
        peek = stream.read(20)
        stream.seek(-len(peek), 1)  # reset to start
        if IndirectPattern.match(peek) is not None:
            return IndirectObject.read_from_stream(stream, pdf)
        else:
            return NumberObject.read_from_stream(stream)

by

    elif tok in b"0123456789+-.":
        # number object OR indirect reference
        peek = stream.read(20)
        stream.seek(-len(peek), 1)  # reset to start
        if IndirectPattern.match(peek) is not None:
            return IndirectObject.read_from_stream(stream, pdf)
        else:
            return NumberObject.read_from_stream(stream)
    else:
        raise PdfReadError(
            f"Invalid Elementary Object starting with {tok} @{stream.tell()}"
        )

References

Severity
6.2 (Medium)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "PyPDF2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.10.5"
            },
            {
              "fixed": "2.10.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.10.5"
      ]
    }
  ],
  "aliases": [
    "CVE-2023-36807"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-835"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2023-06-30T22:19:39Z",
    "nvd_published_at": "2023-06-30T19:15:09Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\nAn attacker who uses this vulnerability can craft a PDF which leads to an infinite loop.\nThis infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted metadata from such a malformed PDF.\n\n### Patches\nThe issue was fixed with https://github.com/py-pdf/pypdf/pull/1331\n\n### Workarounds\nIf you cannot update your version of `PyPDF2` (preferably to `pypdf\u003e3.1.0` as PyPDF2 is deprecated), you should modify `PyPDF2/generic/_data_structures.py::read_object`.\n\nReplace:\n\n```python\n    else:\n        # number object OR indirect reference\n        peek = stream.read(20)\n        stream.seek(-len(peek), 1)  # reset to start\n        if IndirectPattern.match(peek) is not None:\n            return IndirectObject.read_from_stream(stream, pdf)\n        else:\n            return NumberObject.read_from_stream(stream)\n```\n\nby\n\n```python\n    elif tok in b\"0123456789+-.\":\n        # number object OR indirect reference\n        peek = stream.read(20)\n        stream.seek(-len(peek), 1)  # reset to start\n        if IndirectPattern.match(peek) is not None:\n            return IndirectObject.read_from_stream(stream, pdf)\n        else:\n            return NumberObject.read_from_stream(stream)\n    else:\n        raise PdfReadError(\n            f\"Invalid Elementary Object starting with {tok} @{stream.tell()}\"\n        )\n```\n\n### References\n* [pypdf issue #1329](https://github.com/py-pdf/pypdf/issues/1329)\n* [pypdf PR #1331](https://github.com/py-pdf/pypdf/pull/1331)",
  "id": "GHSA-hm9v-vj3r-r55m",
  "modified": "2023-06-30T22:19:39Z",
  "published": "2023-06-30T22:19:39Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/security/advisories/GHSA-hm9v-vj3r-r55m"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-36807"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/issues/1329"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/pull/1331"
    },
    {
      "type": "WEB",
      "url": "https://github.com/py-pdf/pypdf/commit/e6531a25325e7e0174b6a1ba03b57320b5227f6b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/py-pdf/pypdf"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "PyPDF2 vulnerable to possible Infinite Loop when reading malformed objects"
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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