CVE-2026-5439: A memory exhaustion vulnerability exists in ZIP archive processing

Q: How do I fix CVE-2026-5439?

orthanc: upgrade to 1.12.11. Exact commands for each OS are on this page.

Q: Is CVE-2026-5439 being exploited?

CVE-2026-5439 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-5439 affect?

CVE-2026-5439 affects orthanc. Severity is high (CVSS 7.5). 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 cra

Q: How urgent is CVE-2026-5439?

Priority 40/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2026-5439 is a high-severity flaw (CVSS 7.5) affecting orthanc. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 63%)
CISA exploited list	No
Weakness	CWE-770
Published	2026-04-09
Last modified	2026-10-26

Publisher (CNA): CERT/CC · Vendor: orthanc-server

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-09 15:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

orthanc-server orthanc UPGRADE

Affected: < 1.12.11

Fixed in: 1.12.11

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy orthanc || rpm -q orthanc || orthanc --version

2. UPGRADE to 1.12.11 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade orthanc

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade orthanc

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-5439?

orthanc: upgrade to 1.12.11. Exact commands for each OS are on this page.

Is CVE-2026-5439 being exploited?

CVE-2026-5439 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-5439 affect?

CVE-2026-5439 affects orthanc. Severity is high (CVSS 7.5). 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 cra

How urgent is CVE-2026-5439?

Priority 40/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-5442 CRITICAL 9.8 UPGRADE A heap buffer overflow vulnerability exists in the DICOM image decoder
CVE-2026-5443 CRITICAL 9.8 UPGRADE A heap buffer overflow vulnerability exists during the decoding of `PALETTE COLOR` DICOM images
CVE-2026-5445 CRITICAL 9.1 UPGRADE An out-of-bounds read vulnerability exists in the `DecodeLookupTable` function within `DicomImageDecoder.cpp`
CVE-2026-5437 HIGH 7.5 UPGRADE An out-of-bounds read vulnerability exists in `DicomStreamReader` during DICOM meta-header parsing
CVE-2026-5440 HIGH 7.5 UPGRADE A memory exhaustion vulnerability exists in the HTTP server due to unbounded use of the `Content-Length` heade

References

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