CVE-2026-47667 CImg Library: Uncontrolled Memory Allocation and Memory Leak in `_load_analyze()` via Crafted NIfTI/Analyze Header
Attackers can cause denial of service by triggering uncontrolled memory allocation and leaks via crafted NIfTI/Analyze headers in CImg Library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-47667?
CVE-2026-47667 is a high-severity denial of service vulnerability in GreycLab CImg, published on 21 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
CImg Library is a C++ library for image processing. Prior to version 4.0.0 in `_load_analyze()`, the header_size field is read as an `unsigned int` from the first 4 bytes of an Analyze/NIfTI file and passed directly to `new unsigned char[header_size]` without being bounded against the actual file size. A value up to ~4 GB is accepted. If the subsequent `fread` returns `short` as it will for any malformed file), the function throws a `CImgIOException` and the allocated buffer is never freed. A 6-byte crafted file is sufficient to trigger an allocation of ~1.3 GB per call, with the full allocation leaked on every error path. The issue is reachable via `load_analyze()` and the generic `load()` when the file extension is .hdr, .img, or .nii. Version 4.0.0 fixes the issue.
Which versions are affected by CVE-2026-47667?
How do I fix CVE-2026-47667?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-47667 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-47667 exists.
Sources
Also known as DEBIAN-CVE-2026-47667, GHSA-rmfc-grgj-qwhv, UBUNTU-CVE-2026-47667.