CVE-2026-112406
8.7HighPublished 19 Oct 2026 · NVD status: Received · AI triage by gemini-3.8-flash
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Impact
- High impact on availability
- Weakness
- CWE-835
Impact
Remote, unauthenticated attackers can cause a permanent denial of service by exhausting worker CPU capacity. They only need to supply a crafted PDF to an endpoint that appends images to PDFs using Pillow.
Root cause
PdfParser.rewrite_pages() follows Parent relationships without detecting cycles in the page tree, triggering an infinite loop.
Affected systems
Pillow 5.1.0 through 12.x (fixed in 13.0.0)
CVSS v4.0 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Fix & remediation
Upgrade Pillow to version 13.0.0 or later. If upgrading immediately is not possible, reject or sanitize untrusted PDF uploads before passing them to Pillow for image appending.
$ pip install --upgrade 'pillow>=13.0.0'AI-suggested. Run it in staging first and check it against the vendor advisory. Why?
NVD description
Pillow is a Python imaging library. From 5.1.0 until 13.0.0, Pillow can enter an infinite loop while rewriting PDF pages. PdfParser.rewrite_pages() follows Parent relationships without detecting a cycle in the page tree. An attacker can supply a cyclic PDF to an application that appends an image to that PDF. This can hold the worker at full CPU and deny service. This issue is fixed in version 13.0.0.