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CVE-2026-96637— Pillow: Decompression bomb check bypass in SpiderImagePlugin.seek() leads to unbounded allocation DoS

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 方法会重新解析后续的 SPIDER 堆栈帧，并在未重新执行 的情况下直接替换 。攻击者可利用一个极小的文件，通过安全的初始帧通过 的校验，随后在后续的 Mode F 帧中声明极大的图像尺寸。加载该帧时，系统会为攻击者声明的每个像素分配约 4 字节的内存，从而可能导致数 GB 的内存消耗。该问题已在 13.0.0 版本中修复。

CVSS 7.1 · High

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-96637

Vulnerability Information
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Vulnerability Title
Pillow: Decompression bomb check bypass in SpiderImagePlugin.seek() leads to unbounded allocation DoS
Source: CVE Program / CVE List V5
Vulnerability Description
Pillow is a Python imaging library. Prior to 13.0.0, SpiderImageFile.seek() in src/PIL/SpiderImagePlugin.py reparses a later SPIDER stack frame and replaces self._size without rerunning Image._decompression_bomb_check(). A tiny file can use a safe first frame to pass Image.open() and then declare very large dimensions in a later mode F frame. Loading that frame allocates approximately four bytes per attacker-declared pixel and can consume multiple gigabytes of memory. 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
未加控制的资源消耗(资源穷尽)
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-2026-96637

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III. Intelligence Information for CVE-2026-96637

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Patches & Fixes for CVE-2026-96637 (2)

Vendor Advisories for CVE-2026-96637 (1)

Vendor Pages for CVE-2026-96637 (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-2026-96642 7.1 HIGH Pillow: TarIO negative size field causes infinite CPU-spin loop
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-2026-96638 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-400

V. Comments for CVE-2026-96637

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