HAPI FHIR <6.9.4 Auth Bypass via String.startsWith() URL Prefix
CVE-2026-34359 Published on March 31, 2026
HAPI FHIR: Authentication Credential Leakage via Improper URL Prefix Matching on HTTP Redirect in HAPI FHIR Core
HAPI FHIR is a complete implementation of the HL7 FHIR standard for healthcare interoperability in Java. Prior to version 6.9.4, ManagedWebAccessUtils.getServer() uses String.startsWith() to match request URLs against configured server URLs for authentication credential dispatch. Because configured server URLs (e.g., http://tx.fhir.org) lack a trailing slash or host boundary check, an attacker-controlled domain like http://tx.fhir.org.attacker.com matches the prefix and receives Bearer tokens, Basic auth credentials, or API keys when the HTTP client follows a redirect to that domain. This issue has been patched in version 6.9.4.
Vulnerability Analysis
CVE-2026-34359 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2026-34359. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality and integrity, and no impact on availability.
Weakness Type
Origin Validation Error
The software does not properly verify that the source of data or communication is valid.
Affected Versions
hapifhir org.hl7.fhir.core Version < 6.9.4 is affected by CVE-2026-34359Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.