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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-96641
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-21 21:20:32 UTC
Updated2026-10-21 21:20:32 UTC
DescriptionPillow 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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Problem Types: CWE-190 | CWE-190 CWE-190: Integer Overflow or Wraparound

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Python-pillow Pillow affected < 13.0.0 Not specified

References

ReferenceSourceLinkTags
github.com/python-pillow/Pillow/pull/10010 [email protected] github.com
github.com/python-pillow/Pillow/security/advisories/GHSA-4rm8-3hmm-39fg [email protected] github.com
github.com/python-pillow/Pillow/releases/tag/13.0.0 [email protected] github.com
github.com/python-pillow/Pillow/commit/80de4be9e38d3a6148dd4d8491eb80cd1... [email protected] github.com
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