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.
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Wed, 21 Oct 2026 21:00:00 +0000

Type Values Removed Values Added
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.
Title Pillow: TarIO negative size field causes infinite CPU-spin loop
Weaknesses CWE-835
References
Metrics cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-21T20:49:56.989Z

Reserved: 2026-09-23T14:35:50.130Z

Link: CVE-2026-96642

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-21T21:20:32.650

Modified: 2026-10-21T21:20:32.650

Link: CVE-2026-96642

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses