CVE-2026-62295 HAPI FHIR: JSON utility parser unbounded recursion causes StackOverflow denial of service
Attackers can crash HAPI FHIR services by submitting deeply nested JSON, causing stack overflow and denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-62295?
CVE-2026-62295 is a high-severity denial of service vulnerability in hapifhir ca.uhn.hapi.fhir:org.hl7.fhir.r5, published on 7 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. Prior to 6.9.11, the JSON utility parser in org.hl7.fhir.utilities.json.parser.JsonParser enforces no maximum nesting depth for arrays or objects. As a result, a small but deeply nested, syntactically valid FHIR JSON document can trigger unbounded readArray() or readObject() recursion, raising a StackOverflowError before structural validation runs. An attacker who can submit JSON resources for validation can thus crash the request thread, and services that do not isolate StackOverflowError safely may experience worker loss or process instability — a denial-of-service condition. This issue is fixed in version 6.9.11.
Which versions are affected by CVE-2026-62295?
How do I fix CVE-2026-62295?
No fix has been published for CVE-2026-62295 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-62295 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-62295 exists.
Sources
Also known as GHSA-2cq7-hg49-56gc.