vulnerability / NVI-00013978 / Revision 1
HAPI FHIR: SHCParser DEFLATE infinite loop causes denial of service
GitHub lists this reviewed advisory for ca.uhn.hapi.fhir:org.hl7.fhir.r5, ca.uhn.hapi.fhir:org.hl7.fhir.validation, ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.5 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
ca.uhn.hapi.fhir:org.hl7.fhir.r5
source listed<= 6.9.11
### Summary A malformed Smart Health Card (SHC) JWT with `zip: "DEF"` and an empty or truncated DEFLATE payload causes `SHCParser.inflate()` to loop forever. This allows an attacker who can submit SHC content for validation to pin a JVM worker thread indefinitely, causing denial of service. ### Details The vulnerable code is in `org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/SHCParser.java`. `decodeJWT()` inflates the JWT payload when the header contains `"zip":"DEF"`: ```java // SHCParser.java:300-302 if ("DEF".equals(res.header.asString("zip"))) { payloadJson = inflate(payloadJson); } ``` `inflate()` loops only on `!inflater.finished()` and does not check `inflater.needsInput()`, `inflater.needsDictionary()`, or zero-progress output: ```java // SHCParser.java:455-468 while (!inflater.finished()) { final int count = inflater.inflate(buffer); outputStream.write(buffer, 0, count); } ``` For empty or truncated raw DEFLATE input, `Inflater.inflate()` returns `0`, `finished()` remains `false`, and `needsInput()` becomes `true`, producing an infinite tight loop. The same unsafe loop pattern also exists in `decompress()` at `SHCParser.java:410-423`. The validator
ca.uhn.hapi.fhir:org.hl7.fhir.validation
source listed<= 6.9.11
### Summary A malformed Smart Health Card (SHC) JWT with `zip: "DEF"` and an empty or truncated DEFLATE payload causes `SHCParser.inflate()` to loop forever. This allows an attacker who can submit SHC content for validation to pin a JVM worker thread indefinitely, causing denial of service. ### Details The vulnerable code is in `org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/SHCParser.java`. `decodeJWT()` inflates the JWT payload when the header contains `"zip":"DEF"`: ```java // SHCParser.java:300-302 if ("DEF".equals(res.header.asString("zip"))) { payloadJson = inflate(payloadJson); } ``` `inflate()` loops only on `!inflater.finished()` and does not check `inflater.needsInput()`, `inflater.needsDictionary()`, or zero-progress output: ```java // SHCParser.java:455-468 while (!inflater.finished()) { final int count = inflater.inflate(buffer); outputStream.write(buffer, 0, count); } ``` For empty or truncated raw DEFLATE input, `Inflater.inflate()` returns `0`, `finished()` remains `false`, and `needsInput()` becomes `true`, producing an infinite tight loop. The same unsafe loop pattern also exists in `decompress()` at `SHCParser.java:410-423`. The validator
ca.uhn.hapi.fhir:org.hl7.fhir.validation.cli
source listed<= 6.9.11
### Summary A malformed Smart Health Card (SHC) JWT with `zip: "DEF"` and an empty or truncated DEFLATE payload causes `SHCParser.inflate()` to loop forever. This allows an attacker who can submit SHC content for validation to pin a JVM worker thread indefinitely, causing denial of service. ### Details The vulnerable code is in `org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/SHCParser.java`. `decodeJWT()` inflates the JWT payload when the header contains `"zip":"DEF"`: ```java // SHCParser.java:300-302 if ("DEF".equals(res.header.asString("zip"))) { payloadJson = inflate(payloadJson); } ``` `inflate()` loops only on `!inflater.finished()` and does not check `inflater.needsInput()`, `inflater.needsDictionary()`, or zero-progress output: ```java // SHCParser.java:455-468 while (!inflater.finished()) { final int count = inflater.inflate(buffer); outputStream.write(buffer, 0, count); } ``` For empty or truncated raw DEFLATE input, `Inflater.inflate()` returns `0`, `finished()` remains `false`, and `needsInput()` becomes `true`, producing an infinite tight loop. The same unsafe loop pattern also exists in `decompress()` at `SHCParser.java:410-423`. The validator
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-gq9c-wmrm-5hvr ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.