# 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.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Jul 2026
- **Updated:** 23 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-47667, GHSA-rmfc-grgj-qwhv, UBUNTU-CVE-2026-47667

## 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.

Weakness: CWE-789 (Memory Allocation with Excessive Size Value), CWE-401 (Missing Release of Memory after Effective Lifetime), CWE-1284 (Improper Validation of Specified Quantity in Input)

## Which versions are affected by CVE-2026-47667?


## How do I fix CVE-2026-47667?

Upgrade to a fixed version.

## Is CVE-2026-47667 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-47667 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-47667 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-47667 exists.

Affected product: GreycLab CImg. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-47667/ (Markdown: https://insights.sbomify.com/CVE-2026-47667/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-47667
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-47667
- OSV: https://osv.dev/vulnerability/CVE-2026-47667

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-47667/
Summaries are generated and may contain mistakes; the official description above is the record.