CVE-2026-96637Published

Pillow: Decompression bomb check bypass in SpiderImagePlugin.seek() leads to unbounded allocation DoS

Exact source revision recorded 23 Oct 2026 22:48:20 UTC. It does not establish the source's current position. Latest evidence.

Recorded JSON

cve-program · CVE-2026-96637

Published

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 published: 21 Oct 2026 21:01:20 UTC
Source modified: 23 Oct 2026 21:18:59 UTC
Observed here: 23 Oct 2026 22:48:20 UTC
Source terms: CVE Program Terms of Use

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CVSS 4.0 · 7.1 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