CVE-2023-36810: PyPDF2 PyPDF2 Quadratic Runtime With Malformed Vulnerability

MODERATE
Advisory Identifier: GHSA-jrm6-h9cq-8gqw
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CVSS 6.2
CWE-407
Published
Advisory Summary

CVE-2023-36810 is a MODERATE (CVSS 6.2) pypdf2 quadratic runtime with malformed vulnerability (CWE-407: Inefficient Algorithmic Complexity) affecting PyPDF2 libraries in the PyPI ecosystem. The issue involves pypdf2 quadratic runtime with malformed pdf missing xref marker. Remediation is available by upgrading affected packages to version 1.27.9.

CVE-2023-36810 at a Glance

CVE Identifier CVE-2023-36810
GHSA Identifier GHSA-jrm6-h9cq-8gqw
Severity MODERATE
CVSS v3.1 Base Score 6.2
CWE Classification CWE-407: Inefficient Algorithmic Complexity
Affected Product PyPDF2
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-2023-36810

To remediate this vulnerability, upgrade all affected PyPDF2 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

PyPDF2 fixed: 1.27.9 
pip install PyPDF2>=1.27.9
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 PyPDF2

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2023-36810, inspect your installed packages using pip:

pip show PyPDF2

Analyze the terminal output to locate any version of PyPDF2 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.27.9), your application is affected.

Note: The pip show PyPDF2 command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-407: Inefficient Algorithmic Complexity, where an algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached. In PyPDF2, 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 unexpected long runtime. This quadratic runtime blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. ### Patches https://github.com/py-pdf/pypdf/pull/808 ### Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_ ### References * [PyPDF2 PR #808](https://github.com/py-pdf/pypdf/pull/808) * [PyPDF2 Issue #582](https://github.com/py-pdf/pypdf/issues/582)

CVE-2023-36810 Affected PyPDF2 Versions

1 component(s)
Fixed Versions:
1.27.9
Product / Package Ecosystem Affected Versions Fixed Version
PyPDF2
pypi/PyPDF2
PyPI
< 1.27.9
1.27.9

References

GitHub Advisory / Wiki ADVISORY
https://github.com/py-pdf/pypdf/security/advisories/GHSA-jrm6-h9cq-8gqw
NVD — CVE-2023-36810 NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-36810
PyPDF2 Source Repository REPOSITORY
https://github.com/py-pdf/pypdf/issues/582
PyPDF2 Source Repository REPOSITORY
https://github.com/py-pdf/pypdf/pull/808
Security Fix Commit FIX COMMIT
https://github.com/py-pdf/pypdf/commit/c6c56f550bb384e05f0139c796ba1308837d6373
PyPDF2 Source Repository REPOSITORY
https://github.com/py-pdf/pypdf
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2023/07/msg00019.html

Frequently Asked Questions

What is CVE-2023-36810?
CVE-2023-36810 is a security vulnerability in PyPDF2 involving PyPDF2 quadratic runtime with malformed PDF missing xref marker under CWE-407: Inefficient Algorithmic Complexity.
Which PyPDF2 versions are affected?
Affected versions include releases prior to 1.27.9 across affected packages: PyPDF2.
What version fixes CVE-2023-36810?
Upgrading to 1.27.9 (or the latest patched release for your respective branch) resolves the vulnerability.
Is PyPDF2 affected?
Yes, PyPDF2 is affected in releases prior to 1.27.9. Upgrade your dependency to 1.27.9 or later.
What is the CVSS score of CVE-2023-36810?
CVE-2023-36810 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-2023-36810?
CVE-2023-36810 is classified under CWE-407: Inefficient Algorithmic Complexity (An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.).
How can I check PyPI dependencies for CVE-2023-36810?
Run the dependency tree command: 'pip show PyPDF2'. 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-jrm6-h9cq-8gqw",
  "modified" : "2023-06-30T22:17:52Z",
  "published" : "2023-06-30T22:17:52Z",
  "aliases" : [ "CVE-2023-36810" ],
  "summary" : "PyPDF2 quadratic runtime with malformed PDF missing xref marker",
  "details" : "### Impact\nAn attacker who uses this vulnerability can craft a PDF which leads to unexpected long runtime.\nThis quadratic runtime blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage.\n\n### Patches\nhttps://github.com/py-pdf/pypdf/pull/808\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\n### References\n* [PyPDF2 PR #808](https://github.com/py-pdf/pypdf/pull/808)\n* [PyPDF2 Issue #582](https://github.com/py-pdf/pypdf/issues/582)",
  "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" : "PyPDF2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.27.9"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.27.8"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/security/advisories/GHSA-jrm6-h9cq-8gqw"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-36810"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/issues/582"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/pull/808"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/commit/c6c56f550bb384e05f0139c796ba1308837d6373"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/py-pdf/pypdf"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2023/07/msg00019.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-407" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-06-30T22:17:52Z",
    "nvd_published_at" : "2023-06-30T19:15:09Z"
  }
}