CVE-2026-5438: Gzip Decompression Bomb via Content-Encoding Header

Published Apr 9, 2026
·
Updated

A gzip decompression bomb vulnerability exists when Orthanc processes HTTP request with Content-Encoding: gzip. The server does not enforce limits on decompressed size and allocates memory based on attacker-controlled compression metadata. A specially crafted gzip payload can trigger excessive memory allocation and exhaust system memory.

Affected Software

2 affected components
Orthanc Orthanc
Orthanc-server Orthanc<1.12.11

Event History

Apr 9, 2026
CVE Published
via MITRE·02:44 PM
Data Sourced
via MITRE·02:44 PM
DescriptionWeakness
Data Sourced
via NVD·03:16 PM
DescriptionSeverityWeaknessAffected Software
Mar 21, 58260
Event
via FIRST·11:15 AM

Frequently Asked Questions

1

What is the severity of CVE-2026-5438?

CVE-2026-5438 has a severity of high, with a CVSS score of 7.5.

2

What type of vulnerability is CVE-2026-5438?

CVE-2026-5438 is a gzip decompression bomb vulnerability that affects the Orthanc server.

3

How does the CVE-2026-5438 vulnerability exploit memory allocation?

CVE-2026-5438 exploits memory allocation by not enforcing limits on decompressed sizes, allowing excessive memory usage based on attacker-controlled data.

4

How can I mitigate CVE-2026-5438?

To mitigate CVE-2026-5438, ensure that your Orthanc server enforces limits on the decompressed size of gzip payloads.

5

What software is affected by CVE-2026-5438?

CVE-2026-5438 affects the Orthanc server, specifically the Orthanc software.

Contact

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