Vulnerability · Published Apr 9, 2026 · Assigned by certcc
CVE-2026-5438Gzip Decompression Bomb via Content-Encoding Header
High 7.5
In plain English
A high-severity security flaw in DICOM Server from Orthanc. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.5%top 57.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | orthanc | no fix listed | DEBIAN-CVE-2026-5438 |
| Debian:13 | orthanc | no fix listed | DEBIAN-CVE-2026-5438 |
| Debian:14 | orthanc | 1.12.10+dfsg-4 | DEBIAN-CVE-2026-5438 |
| Ubuntu:22.04:LTS | orthanc | no fix listed | UBUNTU-CVE-2026-5438 |
| Ubuntu:24.04:LTS | orthanc | no fix listed | UBUNTU-CVE-2026-5438 |
| Ubuntu:25.10 | orthanc | no fix listed | UBUNTU-CVE-2026-5438 |
| Ubuntu:26.04:LTS | orthanc | no fix listed | UBUNTU-CVE-2026-5438 |
| Ubuntu:26.10 | orthanc | no fix listed | UBUNTU-CVE-2026-5438 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Orthanc | DICOM Server | 0 – through 1.12.10 |