CVE-2026-96641

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

MEDIUM
6.5
CVSS Score
Published: October 21, 2026 at 08:51 PM UTC
Updated: October 22, 2026 at 04:46 PM UTC
1 product affected across 1 vendorPillow

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.4%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

CVSS

6.5MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusUNDERGOING ANALYSIS
CWE
CWE-190

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