High severity · published Apr 9, 2026
CVE-2026-5439
Memory Exhaustion via Forged ZIP Metadata
7.5
CVSS
0.4%
EPSS
No
On KEV
Description
A memory exhaustion vulnerability exists in ZIP archive processing. Orthanc automatically extracts ZIP archives uploaded to certain endpoints and trusts metadata fields describing the uncompressed size of archived files. An attacker can craft a small ZIP archive containing a forged size value, causing the server to allocate extremely large buffers during extraction.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 37% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
DS
DICOM Server · Orthanc
through 1.12.10 · source: vendor
OR
Orthanc · Orthanc-server
before 1.12.11 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-5439
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-5439
Third Party Advisory
https://kb.cert.org/vuls/id/536588
Not Applicable
https://www.machinespirits.de/
Product
https://www.orthanc-server.com/
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