CVE-2023-36464: Pypdf Pypdf And PyPDF2 Possible Infinite Vulnerability

MODERATE
Advisory Identifier: GHSA-4vvm-4w3v-6mr8
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CVSS 6.2
CWE-835
Published
Advisory Summary

CVE-2023-36464 is a MODERATE (CVSS 6.2) pypdf and pypdf2 possible infinite vulnerability (CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')) affecting Pypdf libraries in the PyPI ecosystem. The issue involves pypdf and pypdf2 possible infinite loop when a comment isn't followed by a character. Remediation is available by upgrading affected packages to version 3.9.0.

CVE-2023-36464 at a Glance

CVE Identifier CVE-2023-36464
GHSA Identifier GHSA-4vvm-4w3v-6mr8
Severity MODERATE
CVSS v3.1 Base Score 6.2
CWE Classification CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
Affected Product Pypdf
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 6.2

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2023-36464

To remediate this vulnerability, upgrade all affected Pypdf dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

pypdf fixed: 3.9.0 
pip install pypdf>=3.9.0
PyPDF2 fixed: Latest secure release 
pip install PyPDF2>=Latest secure release
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show pypdf

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2023-36464, inspect your installed packages using pip:

pip show pypdf

Analyze the terminal output to locate any version of Pypdf in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.9.0), your application is affected.

Note: The pip show pypdf command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop'), where the product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. In Pypdf, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop if `__parse_content_stream` is executed. 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 text from such a PDF. Example Code and a PDF that causes the issue: ```python from pypdf import PdfReader # https://objects.githubusercontent.com/github-production-repository-file-5c1aeb/3119517/11367871?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20230627%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20230627T201018Z&X-Amz-Expires=300&X-Amz-Signature=d71c8fd9181c4875f0c04d563b6d32f1d4da6e7b2e6be2f14479ce4ecdc9c8b2&X-Amz-SignedHeaders=host&actor_id=1658117&key_id=0&repo_id=3119517&response-content-disposition=attachment%3Bfilename%3DMiFO_LFO_FEIS_NOA_Published.3.pdf&response-content-type=application%2Fpdf reader = PdfReader("MiFO_LFO_FEIS_NOA_Published.3.pdf") page = reader.pages[0] page.extract_text() ``` The issue was introduced with https://github.com/py-pdf/pypdf/pull/969 ### Patches The issue was fixed with https://github.com/py-pdf/pypdf/pull/1828 ### Workarounds It is recommended to upgrade to `pypdf>=3.9.0`. PyPDF2 users should migrate to pypdf. If you cannot update your version of pypdf, you should modify `pypdf/generic/_data_structures.py`: ``` OLD: while peek not in (b"\r", b"\n"): NEW: while peek not in (b"\r", b"\n", b""): ```

CVE-2023-36464 Affected Pypdf Versions

2 component(s)
Fixed Versions:
3.9.0
Product / Package Ecosystem Affected Versions Fixed Version
pypdf
pypi/pypdf
PyPI
≥ 3.1.0
< 3.9.0
3.9.0
PyPDF2
pypi/PyPDF2
PyPI
≥ 2.2.0
≤ 3.0.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/py-pdf/pypdf/security/advisories/GHSA-4vvm-4w3v-6mr8
NVD — CVE-2023-36464 NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-36464
Pypdf Source Repository REPOSITORY
https://github.com/py-pdf/pypdf/pull/1828
Pypdf Source Repository REPOSITORY
https://github.com/py-pdf/pypdf/pull/969
Security Fix Commit FIX COMMIT
https://github.com/py-pdf/pypdf/commit/b0e5c689df689ab173df84dacd77b6fc3c161932
Pypdf Source Repository REPOSITORY
https://github.com/py-pdf/pypdf
Pypdf Release RELEASE
https://github.com/py-pdf/pypdf/releases/tag/3.9.0

Frequently Asked Questions

What is CVE-2023-36464?
CVE-2023-36464 is a security vulnerability in Pypdf involving pypdf and PyPDF2 possible Infinite Loop when a comment isn't followed by a character under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop').
Which Pypdf versions are affected?
Affected versions include releases prior to 3.9.0 across affected packages: pypdf, PyPDF2.
What version fixes CVE-2023-36464?
Upgrading to 3.9.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is pypdf affected?
Yes, pypdf is affected in releases prior to 3.9.0. Upgrade your dependency to 3.9.0 or later.
Is PyPDF2 affected?
Yes, PyPDF2 is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2023-36464?
CVE-2023-36464 has a CVSS v3.1 base score of 6.2 (MODERATE) with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2023-36464?
CVE-2023-36464 is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') (The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.).
How can I check PyPI dependencies for CVE-2023-36464?
Run the dependency tree command: 'pip show pypdf'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4vvm-4w3v-6mr8",
  "modified" : "2023-07-07T17:19:37Z",
  "published" : "2023-06-30T20:33:57Z",
  "aliases" : [ "CVE-2023-36464" ],
  "summary" : "pypdf and PyPDF2 possible Infinite Loop when a comment isn't followed by a character",
  "details" : "### Impact\nAn attacker who uses this vulnerability can craft a PDF which leads to an infinite loop if `__parse_content_stream` is executed. 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 text from such a PDF.\n\nExample Code and a PDF that causes the issue:\n\n```python\nfrom pypdf import PdfReader\n\n# https://objects.githubusercontent.com/github-production-repository-file-5c1aeb/3119517/11367871?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20230627%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20230627T201018Z&X-Amz-Expires=300&X-Amz-Signature=d71c8fd9181c4875f0c04d563b6d32f1d4da6e7b2e6be2f14479ce4ecdc9c8b2&X-Amz-SignedHeaders=host&actor_id=1658117&key_id=0&repo_id=3119517&response-content-disposition=attachment%3Bfilename%3DMiFO_LFO_FEIS_NOA_Published.3.pdf&response-content-type=application%2Fpdf\nreader = PdfReader(\"MiFO_LFO_FEIS_NOA_Published.3.pdf\")\npage = reader.pages[0]\npage.extract_text()\n```\n\nThe issue was introduced with https://github.com/py-pdf/pypdf/pull/969\n\n### Patches\n\nThe issue was fixed with https://github.com/py-pdf/pypdf/pull/1828\n\n### Workarounds\n\nIt is recommended to upgrade to `pypdf>=3.9.0`. PyPDF2 users should migrate to pypdf.\n\nIf you cannot update your version of pypdf, you should modify `pypdf/generic/_data_structures.py`:\n\n```\nOLD: while peek not in (b\"\\r\", b\"\\n\"):\nNEW: while peek not in (b\"\\r\", b\"\\n\", b\"\"):\n```",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "pypdf"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.1.0"
      }, {
        "fixed" : "3.9.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "PyPDF2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.2.0"
      }, {
        "last_affected" : "3.0.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/security/advisories/GHSA-4vvm-4w3v-6mr8"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-36464"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/pull/1828"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/pull/969"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/commit/b0e5c689df689ab173df84dacd77b6fc3c161932"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/py-pdf/pypdf"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/releases/tag/3.9.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-835" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-06-30T20:33:57Z",
    "nvd_published_at" : "2023-06-27T22:15:11Z"
  }
}