# CVE-2026-5437: Out-of-Bounds Read in DicomStreamReader

> An out-of-bounds read in Orthanc DICOM server allows attackers to potentially read memory contents via malformed metadata, requiring a patch.

- **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:** 9 Apr 2026
- **Updated:** 14 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-5437, GHSA-gqwr-8hwp-hh46, UBUNTU-CVE-2026-5437

## What is CVE-2026-5437?

CVE-2026-5437 is a high-severity vulnerability in Orthanc DICOM Server, published on 9 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An out-of-bounds read vulnerability exists in `DicomStreamReader` during DICOM meta-header parsing. When processing malformed metadata structures, the parser may read beyond the bounds of the allocated metadata buffer. Although this issue does not typically crash the server or expose data directly to the attacker, it reflects insufficient input validation in the parsing logic.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-5437?

It affects 1 product.


Products: Orthanc-Server Orthanc.

## How do I fix CVE-2026-5437?

Apply the vendor's patch.

## Is CVE-2026-5437 being exploited?

There is no known exploitation of CVE-2026-5437 in the wild and no public exploit code.

## Other vulnerabilities in Orthanc DICOM Server

- [CVE-2026-5442](https://insights.sbomify.com/CVE-2026-5442/): Heap Buffer Overflow in DICOM Image Decoder via VR UL Dimensions (critical 9.8)
- [CVE-2026-5443](https://insights.sbomify.com/CVE-2026-5443/): Heap Buffer Overflow in DICOM Image Decoder (Palette Color Decode) (critical 9.8)
- [CVE-2025-0896](https://insights.sbomify.com/CVE-2025-0896/): Orthanc Server Missing Authentication for Critical Function (critical 9.2)
- [CVE-2026-5445](https://insights.sbomify.com/CVE-2026-5445/): Out-of-Bounds Read in DicomImageDecoder (DecodeLookupTable) (critical 9.1)
- [CVE-2023-33466](https://insights.sbomify.com/CVE-2023-33466/): Path traversal in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5437 and fix it if it is affected.

What it is: CVE-2026-5437 is a high-severity vulnerability in Orthanc DICOM Server, published on 9 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-5437 in the wild and no public exploit code.

Affected product: Orthanc DICOM Server. 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-2026-5437/ (Markdown: https://insights.sbomify.com/CVE-2026-5437/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5437
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5437
- OSV: https://osv.dev/vulnerability/CVE-2026-5437

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5437/
Summaries are generated and may contain mistakes; the official description above is the record.