CVE-2026-42308: Pillow Pillow Has An Integer Overflow Vulnerability

MODERATE
Advisory Identifier: GHSA-wjx4-4jcj-g98j
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CVSS 5.5
CWE-190
Published
Advisory Summary

CVE-2026-42308 is a MODERATE (CVSS 5.5) pillow has an integer overflow vulnerability (CWE-190: Integer Overflow or Wraparound) affecting Pillow libraries in the PyPI ecosystem. The issue involves pillow has an integer overflow when processing fonts. Remediation is available by upgrading affected packages to version 12.2.0.

CVE-2026-42308 at a Glance

CVE Identifier CVE-2026-42308
GHSA Identifier GHSA-wjx4-4jcj-g98j
Severity MODERATE
CVSS v3.1 Base Score 5.5
CWE Classification CWE-190: Integer Overflow or Wraparound
Affected Product Pillow
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.5

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

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
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-2026-42308

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

pillow fixed: 12.2.0 
pip install pillow>=12.2.0
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 pillow

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-42308, inspect your installed packages using pip:

pip show pillow

Analyze the terminal output to locate any version of Pillow in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 12.2.0), your application is affected.

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

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-190: Integer Overflow or Wraparound, where the product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. this occurs when an integer value is incremented to a value that is too large to store in the associated representation. when this occurs, the value may become a very small or negative number. In Pillow, 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

If a font advances for each glyph by an exceeding large amount, when Pillow keeps track of the current position, it may lead to an integer overflow. This has been fixed.

CVE-2026-42308 Affected Pillow Versions

1 component(s)
Fixed Versions:
12.2.0
Product / Package Ecosystem Affected Versions Fixed Version
pillow
pypi/pillow
PyPI
< 12.2.0
12.2.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/python-pillow/Pillow/security/advisories/GHSA-wjx4-4jcj-g98j
NVD — CVE-2026-42308 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42308
Pillow Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/pillow/PYSEC-2026-165.yaml
Pillow Source Repository REPOSITORY
https://github.com/python-pillow/Pillow
Pillow Release RELEASE
https://github.com/python-pillow/Pillow/releases/tag/12.2.0

Frequently Asked Questions

What is CVE-2026-42308?
CVE-2026-42308 is a security vulnerability in Pillow involving Pillow has an integer overflow when processing fonts under CWE-190: Integer Overflow or Wraparound.
Which Pillow versions are affected?
Affected versions include releases prior to 12.2.0 across affected packages: pillow.
What version fixes CVE-2026-42308?
Upgrading to 12.2.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is pillow affected?
Yes, pillow is affected in releases prior to 12.2.0. Upgrade your dependency to 12.2.0 or later.
What is the CVSS score of CVE-2026-42308?
CVE-2026-42308 has a CVSS v3.1 base score of 5.5 (MODERATE) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-42308?
CVE-2026-42308 is classified under CWE-190: Integer Overflow or Wraparound (The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.).
How can I check PyPI dependencies for CVE-2026-42308?
Run the dependency tree command: 'pip show pillow'. 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-wjx4-4jcj-g98j",
  "modified" : "2026-06-08T23:40:21Z",
  "published" : "2026-05-04T20:18:45Z",
  "aliases" : [ "CVE-2026-42308" ],
  "summary" : "Pillow has an integer overflow when processing fonts",
  "details" : "If a font advances for each glyph by an exceeding large amount, when Pillow keeps track of the current position, it may lead to an integer overflow. This has been fixed.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/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" : "pillow"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "12.2.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/python-pillow/Pillow/security/advisories/GHSA-wjx4-4jcj-g98j"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42308"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/pillow/PYSEC-2026-165.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/python-pillow/Pillow"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/python-pillow/Pillow/releases/tag/12.2.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-190" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-04T20:18:45Z",
    "nvd_published_at" : "2026-05-09T06:16:09Z"
  }
}