CVE-2026-96778: Pillow: Heap buffer overflow writing JPEG comment after ICC profile fills buffer
Pillow is a Python imaging library. From 9.4.0 until 13.0.0, ImagingJpegEncode() in src/libImaging/JpegEncode.c can call jpegwritemarker() for a JPEG COM comment when an ICC profile has exactly filled the 65536-byte encoder buffer. libjpeg writes one byte before checking the exhausted freeinbuffer counter, which then wraps and permits the attacker-controlled comment and subsequent compressed image data to overwrite adjacent heap memory. Re-saving an untrusted image as JPEG while preserving its ICC profile and forwarded comment can crash the process and may enable code execution in suitable runtime and heap layouts. This issue is fixed in version 13.0.0.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Pillowto a version that resolves this vulnerability.Fixed in 13.0.0
Event History
Frequently Asked Questions
Which Pillow versions need to be remediated?
Pillow versions from 9.4.0 up to, but not including, 13.0.0 are affected. Upgrade to version 13.0.0.
What application behavior makes exploitation possible?
The vulnerable path is reached when an application re-saves an untrusted image as JPEG while preserving both its ICC profile and a forwarded JPEG comment. The ICC profile must exactly fill the 65536-byte encoder buffer.
What is the likely impact for exposed services?
Processing a crafted image can crash the process. Code execution may also be possible depending on the runtime and heap layout.