CVE-2026-59938: pypdf Possible Large Memory Usage For Vulnerability

MODERATE
Advisory Identifier: GHSA-5qjq-93h5-hrgp
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CWE-789
Published
Advisory Summary

CVE-2026-59938 is a MODERATE possible large memory usage for vulnerability (CWE-789: Memory Allocation with Excessive Size Value) affecting pypdf libraries in the PyPI ecosystem. The issue involves possible large memory usage for wrong image dimensions. Remediation is available by upgrading affected packages to version 6.14.0.

CVE-2026-59938 at a Glance

CVE Identifier CVE-2026-59938
GHSA Identifier GHSA-5qjq-93h5-hrgp
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-789: Memory Allocation with Excessive Size Value
Affected Product pypdf
Package Ecosystem PyPI
Published Date
Last Updated

How to Fix CVE-2026-59938

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: 6.14.0 
pip install pypdf>=6.14.0
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-2026-59938, 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 6.14.0), 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-789: Memory Allocation with Excessive Size Value, where the product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated. 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 large memory usage. This requires loading images where the declared size values are much too large compared to the actual data. ### Patches This has been fixed in [pypdf==6.14.0](https://github.com/py-pdf/pypdf/releases/tag/6.14.0). ### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#3888](https://github.com/py-pdf/pypdf/pull/3888).

CVE-2026-59938 Affected pypdf Versions

1 component(s)
Fixed Versions:
6.14.0
Product / Package Ecosystem Affected Versions Fixed Version
pypdf
pypi/pypdf
PyPI
< 6.14.0
6.14.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/py-pdf/pypdf/security/advisories/GHSA-5qjq-93h5-hrgp
NVD — CVE-2026-59938 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59938
pypdf Source Repository REPOSITORY
https://github.com/py-pdf/pypdf/pull/3888
Security Fix Commit FIX COMMIT
https://github.com/py-pdf/pypdf/commit/c64583be16b8e8763d8777075f8ecbf382014b7a
pypdf Source Repository REPOSITORY
https://github.com/py-pdf/pypdf
pypdf Release RELEASE
https://github.com/py-pdf/pypdf/releases/tag/6.14.0

Frequently Asked Questions

What is CVE-2026-59938?
CVE-2026-59938 is a security vulnerability in pypdf involving Possible large memory usage for wrong image dimensions under CWE-789: Memory Allocation with Excessive Size Value.
Which pypdf versions are affected?
Affected versions include releases prior to 6.14.0 across affected packages: pypdf.
What version fixes CVE-2026-59938?
Upgrading to 6.14.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is pypdf affected?
Yes, pypdf is affected in releases prior to 6.14.0. Upgrade your dependency to 6.14.0 or later.
What CWE is associated with CVE-2026-59938?
CVE-2026-59938 is classified under CWE-789: Memory Allocation with Excessive Size Value (The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.).
How can I check PyPI dependencies for CVE-2026-59938?
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-5qjq-93h5-hrgp",
  "modified" : "2026-07-23T15:06:58Z",
  "published" : "2026-07-23T15:06:58Z",
  "aliases" : [ "CVE-2026-59938" ],
  "summary" : "pypdf: Possible large memory usage for wrong image dimensions",
  "details" : "### Impact\n\nAn attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires loading images where the declared size values are much too large compared to the actual data.\n\n### Patches\n\nThis has been fixed in [pypdf==6.14.0](https://github.com/py-pdf/pypdf/releases/tag/6.14.0).\n\n### Workarounds\n\nIf you cannot upgrade yet, consider applying the changes from PR [#3888](https://github.com/py-pdf/pypdf/pull/3888).",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "pypdf"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "6.14.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/security/advisories/GHSA-5qjq-93h5-hrgp"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-59938"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/pull/3888"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/commit/c64583be16b8e8763d8777075f8ecbf382014b7a"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/py-pdf/pypdf"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/py-pdf/pypdf/releases/tag/6.14.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-789" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-23T15:06:58Z",
    "nvd_published_at" : "2026-07-08T18:16:35Z"
  }
}