Pillow: BMP RLE decoder memory-amplification DoS via unbounded delta escape / absolute mode

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-96638
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. From 9.1.0 until 13.0.0, BmpRleDecoder.decode() in src/PIL/BmpImagePlugin.py permits crafted RLE BMP delta escapes and absolute-mode runs to append beyond the remaining dest_length without a per-branch cap. A delta can add roughly 255 image rows in one iteration, so a kilobyte-sized file with a large but permitted width can expand the data bytearray to hundreds of megabytes or more, causing memory-exhaustion denial of service. 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-400 | CWE-770 | CWE-400 CWE-400: Uncontrolled Resource Consumption | CWE-770 CWE-770: Allocation of Resources Without Limits or Throttling

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 >= 9.1.0, < 13.0.0 Not specified

References

ReferenceSourceLinkTags
github.com/python-pillow/Pillow/security/advisories/GHSA-24rc-8hj2-v98c [email protected] github.com
github.com/python-pillow/Pillow/pull/10015 [email protected] github.com
github.com/python-pillow/Pillow/releases/tag/13.0.0 [email protected] github.com
github.com/python-pillow/Pillow/commit/e7794835e323ff2691d9b3a974cade1a4... [email protected] github.com
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