CVE-2026-96638

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

MEDIUM
6.5
CVSS Score
Published: October 21, 2026 at 08:47 PM UTC
Updated: October 28, 2026 at 07:19 PM UTC
2 products affected across 2 vendorsPillowPillow

Using Pillow by python-pillow?

Get instant alerts when new vulnerabilities affect Pillow - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
MEDIUM6.5
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

Pillow 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.

Affected

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

9.1.0 ≤ v < 13.0.0

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (4)

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

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

StatusANALYZED
CWE
CWE-400CWE-770

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card