CVE-2026-96642

Pillow: TarIO negative size field causes infinite CPU-spin loop

MEDIUM
6.5
CVSS Score
Published: October 21, 2026 at 08:49 PM UTC
Updated: October 27, 2026 at 02:26 PM UTC
2 products affected across 2 vendorsPillowPillow

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.3%

Description

Pillow is a Python imaging library. Prior to 13.0.0, the TarIO initializer in src/PIL/TarIO.py accepts a negative octal member size and computes a backward seek that returns to the same 512-byte header. When the requested member name does not match, the parser repeatedly reads that header, consumes a full CPU core, and never returns. TarIO is reached only when an application directly uses PIL.TarIO.TarIO rather than the default Image.open() path. 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.

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)

CVSS

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

Quick Info

StatusANALYZED
CWE
CWE-835

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