Infinite loop in Pillow - #VU127176
Published: April 23, 2026
Vulnerability identifier: #VU127176
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: N/A
CWE-ID: CWE-835
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Alex Clark and Contributors
Affected software:
Pillow
Pillow
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to an infinite loop in PdfParser when parsing a malicious PDF trailer with cyclic Prev pointers. A remote attacker can supply a specially crafted PDF file to cause a denial of service.
The issue can cause the process to hang indefinitely, consume 100% CPU, and make the application unresponsive.
Remediation
Install security update from vendor's website.