CVE-2026-96641

Pillow: Reachable undefined behavior in native integer operations, potentially leading to denial of service or logic integrity compromise

Published Oct 21, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
Description
Pillow is a Python imaging library. Prior to 13.0.0, PILfont text-width accumulation in src/_imaging.c checks positive glyph advances against INT_MAX but does not check negative advances against INT_MIN. Repeating a signed 16-bit advance of -32768 can therefore execute a signed C integer overflow in xsize += dx, producing a large positive width from a negative mathematical result. Applications that use getlength(), getsize(), or derived layout, quota, serialization, or allocation calculations can experience logic-integrity errors or resource consumption, while the high-level mask path commonly retains a decompression-bomb check. This issue is fixed in version 13.0.0.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-4rm8-3hmm-39fg Pillow: Reachable undefined behavior in native integer operations, potentially leading to denial of service or logic integrity compromise
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Python
Python pillow
CPEs cpe:2.3:a:python:pillow:*:*:*:*:*:*:*:*
Vendors & Products Python
Python pillow
Type Values Removed Values Added
First Time appeared Python-pillow
Python-pillow pillow
Vendors & Products Python-pillow
Python-pillow pillow
Type Values Removed Values Added
Description Pillow is a Python imaging library. Prior to 13.0.0, PILfont text-width accumulation in src/_imaging.c checks positive glyph advances against INT_MAX but does not check negative advances against INT_MIN. Repeating a signed 16-bit advance of -32768 can therefore execute a signed C integer overflow in xsize += dx, producing a large positive width from a negative mathematical result. Applications that use getlength(), getsize(), or derived layout, quota, serialization, or allocation calculations can experience logic-integrity errors or resource consumption, while the high-level mask path commonly retains a decompression-bomb check. This issue is fixed in version 13.0.0.
Title Pillow: Reachable undefined behavior in native integer operations, potentially leading to denial of service or logic integrity compromise
Weaknesses CWE-190
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Oct 28, 2026, 1:50 AM
Reserved
Sep 23, 2026, 2:35 PM
Status
Analyzed
Published
Oct 21, 2026, 9:20 PM
Modified
Oct 28, 2026, 2:17 AM
Severity
Moderate
Public date
Oct 21, 2026, 8:51 PM