CVE-2026-5439Network attack vector

Server termination via unbounded ZIP allocation

Published Apr 9, 2026 · Updated Apr 9, 2026

Memory exhaustion in Orthanc 1.12.10 and earlier allows remote attackers to terminate the server via a crafted ZIP upload. ZipReader::ReadNextFile trusts the central-directory uncompressed_size field and resizes an output buffer without an upper bound. Reaching POST /instances is required; authentication gates the request where enabled, and one small archive can exhaust memory and terminate the process.

CVSS severity7.5
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory exhaustion in Orthanc 1.12.10 and earlier allows remote attackers to terminate the server via a crafted ZIP upload. ZipReader::ReadNextFile trusts the central-directory uncompressed_size field and resizes an output buffer without an upper bound. Reaching POST /instances is required; authentication gates the request where enabled, and one small archive can exhaust memory and terminate the process.

The record

CVE
CVE-2026-5439
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Orthanc
Product
Orthanc
Classifications
CWE-770, T1499
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Apr 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=1.12.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Orthanc · Orthancversion=0 <=1.12.10

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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