How severe is CVE-2026-5438?

CVE-2026-5438 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-5438 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-5438?

CVE-2026-5438 affects Orthanc-server Orthanc. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-5438?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-5438 have an EU (EUVD) identifier?

Yes. CVE-2026-5438 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-20914.

When was CVE-2026-5438 published?

CVE-2026-5438 was published on 2026-04-09 and last updated on 2026-06-17.

CVE-2026-5438

CVE-2026-5438 is a high-severity vulnerability in Orthanc-server Orthanc with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (38th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-20914
Weakness: CWE-770
Affected product: Orthanc-server Orthanc
Published: 2026-04-09
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-5438?: 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.
How severe is CVE-2026-5438?: CVE-2026-5438 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-5438 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-5438?: CVE-2026-5438 affects Orthanc-server Orthanc. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-5438?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-5438 have an EU (EUVD) identifier?: Yes. CVE-2026-5438 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-20914.
When was CVE-2026-5438 published?: CVE-2026-5438 was published on 2026-04-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:orthanc-server:orthanc:*:*:*:*:*:*:*:*

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