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CVE-2026-96642— Pillow: TarIO negative size field causes infinite CPU-spin loop

Quick assessment

Affected
python-pillow Pillow
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Pillow 是一个 Python 图像处理库。在 13.0.0 版本之前， 中的 初始化器会接受负的八进制成员大小，并计算一个向后 seek 操作，该操作会返回到同一个 512 字节的文件头。当请求的成员名称不匹配时，解析器会反复读取该文件头，占用一个完整的 CPU 核心，且永远不会返回。 仅在应用程序直接使用 （而非默认的 路径）时才会被调用。该问题已在 13.0.0 版本中修复。

CVSS 7.1 · High

Possible ATT&CK Techniques 1 AI

T1499.003 · Application Exhaustion Flood
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I. Basic Information for CVE-2026-96642

Vulnerability Information
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Vulnerability Title
Pillow: TarIO negative size field causes infinite CPU-spin loop
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
不可达退出条件的循环(无限循环)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
python-pillow Pillow < 13.0.0 -

II. Public POCs for CVE-2026-96642

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III. Intelligence Information for CVE-2026-96642

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Patches & Fixes for CVE-2026-96642 (2)

Vendor Advisories for CVE-2026-96642 (1)

Vendor Pages for CVE-2026-96642 (1)

Same Patch Batch · python-pillow · 2026-10-21 · 11 CVEs total

CVE-2026-96639 9.8 CRITICAL Pillow multi-frame loaders can reuse stale native image storage after mode transitions
CVE-2026-96640 8.2 HIGH Pillow PDF append accepts malformed shared page-tree DAG causing resource exhaustion
CVE-2026-96778 7.7 HIGH Pillow: Heap buffer overflow writing JPEG comment after ICC profile fills buffer
CVE-2026-96643 7.1 HIGH Pillow: PNG eXIf chunk makes EXIF parsing run in quadratic time
CVE-2026-96644 7.1 HIGH Pillow: Heap over-read in WMF/EMF rendering via 16-bit dimension truncation (Windows build
CVE-2026-96637 7.1 HIGH Pillow: Decompression bomb check bypass in SpiderImagePlugin.seek() leads to unbounded all
CVE-2026-96638 6.5 MEDIUM Pillow: BMP RLE decoder memory-amplification DoS via unbounded delta escape / absolute mod
CVE-2026-96641 6.5 MEDIUM Pillow: Reachable undefined behavior in native integer operations, potentially leading to
CVE-2026-96636 6.5 MEDIUM Pillow: Decompression-bomb protection bypass via multi-frame seek() in MPO and DCX (MpoIma
CVE-2026-114501 6.3 MEDIUM Pillow: Arrow export leaks stale heap memory when PILLOW_ALIGNMENT > 1

IV. Related Vulnerabilities

Same product: Pillow
Same vendor: python-pillow
Same weakness: CWE-835

V. Comments for CVE-2026-96642

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