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Medium severity · published Oct 21, 2026
CVE-2026-96642
Pillow: TarIO negative size field causes infinite CPU-spin loop
New
6.5
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 34% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PI
Pillow · python-pillow
< 13.0.0 · source: vendor, NVD
Affected product
PI
Pillow
python-pillow
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-96642
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-96642
Patch
https://github.com/python-pillow/Pillow/commit/19b695fdcc5eddc37374e2b1645fc4185edaf71d
Issue Tracking
https://github.com/python-pillow/Pillow/pull/10012
Release Notes
https://github.com/python-pillow/Pillow/releases/tag/13.0.0
Vendor Advisory
https://github.com/python-pillow/Pillow/security/advisories/GHSA-3j72-p6qg-6xp7
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