vulnerability / NVI-00013933 / Revision 1
Http4s Ember accepts Transfer-Encoding combined with Content-Length (CL.TE request smuggling)
GitHub lists this reviewed advisory for org.http4s:http4s-ember-core_2.12, org.http4s:http4s-ember-core_2.13, org.http4s:http4s-ember-core_3, org.http4s:http4s-ember-core_2.13, org.http4s:http4s-ember-core_3. 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.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
org.http4s:http4s-ember-core_2.12
source listed<= 0.23.34
## Summary Ember's HTTP/1.1 request parser does not reject a message that carries both a `Transfer-Encoding` and a `Content-Length` header. RFC 9112 §6.1 requires a server to treat such a message as a framing error and close the connection. An intermediary that follows the RFC's CL-strip-and-forward path (or that prioritises `Content-Length`) will frame the body differently from Ember, enabling HTTP request smuggling (CL.TE). ## Impact ### Server Request smuggling when ember-server is an origin behind an intermediary that forwards both headers over a keep-alive backend connection and frames by `Content-Length` while Ember frames by chunked: - Front-end security bypass: the smuggled request reaches paths the intermediary's ACL/auth layer would have blocked, with attacker-chosen method and headers. - Cross-user request hijack: a dangling smuggled prefix concatenates with the next victim's request on the shared backend socket, capturing its headers. - Cache poisoning: the smuggled response is associated with the next request key in a caching proxy. ### Client ember-client shares the same parser on the response path. An upstream that sends both headers can desync a poole
org.http4s:http4s-ember-core_2.13
source listed<= 0.23.34
## Summary Ember's HTTP/1.1 request parser does not reject a message that carries both a `Transfer-Encoding` and a `Content-Length` header. RFC 9112 §6.1 requires a server to treat such a message as a framing error and close the connection. An intermediary that follows the RFC's CL-strip-and-forward path (or that prioritises `Content-Length`) will frame the body differently from Ember, enabling HTTP request smuggling (CL.TE). ## Impact ### Server Request smuggling when ember-server is an origin behind an intermediary that forwards both headers over a keep-alive backend connection and frames by `Content-Length` while Ember frames by chunked: - Front-end security bypass: the smuggled request reaches paths the intermediary's ACL/auth layer would have blocked, with attacker-chosen method and headers. - Cross-user request hijack: a dangling smuggled prefix concatenates with the next victim's request on the shared backend socket, capturing its headers. - Cache poisoning: the smuggled response is associated with the next request key in a caching proxy. ### Client ember-client shares the same parser on the response path. An upstream that sends both headers can desync a poole
org.http4s:http4s-ember-core_3
source listed<= 0.23.34
## Summary Ember's HTTP/1.1 request parser does not reject a message that carries both a `Transfer-Encoding` and a `Content-Length` header. RFC 9112 §6.1 requires a server to treat such a message as a framing error and close the connection. An intermediary that follows the RFC's CL-strip-and-forward path (or that prioritises `Content-Length`) will frame the body differently from Ember, enabling HTTP request smuggling (CL.TE). ## Impact ### Server Request smuggling when ember-server is an origin behind an intermediary that forwards both headers over a keep-alive backend connection and frames by `Content-Length` while Ember frames by chunked: - Front-end security bypass: the smuggled request reaches paths the intermediary's ACL/auth layer would have blocked, with attacker-chosen method and headers. - Cross-user request hijack: a dangling smuggled prefix concatenates with the next victim's request on the shared backend socket, capturing its headers. - Cache poisoning: the smuggled response is associated with the next request key in a caching proxy. ### Client ember-client shares the same parser on the response path. An upstream that sends both headers can desync a poole
org.http4s:http4s-ember-core_2.13
source listed>= 1.0.0-M1, <= 1.0.0-M46
## Summary Ember's HTTP/1.1 request parser does not reject a message that carries both a `Transfer-Encoding` and a `Content-Length` header. RFC 9112 §6.1 requires a server to treat such a message as a framing error and close the connection. An intermediary that follows the RFC's CL-strip-and-forward path (or that prioritises `Content-Length`) will frame the body differently from Ember, enabling HTTP request smuggling (CL.TE). ## Impact ### Server Request smuggling when ember-server is an origin behind an intermediary that forwards both headers over a keep-alive backend connection and frames by `Content-Length` while Ember frames by chunked: - Front-end security bypass: the smuggled request reaches paths the intermediary's ACL/auth layer would have blocked, with attacker-chosen method and headers. - Cross-user request hijack: a dangling smuggled prefix concatenates with the next victim's request on the shared backend socket, capturing its headers. - Cache poisoning: the smuggled response is associated with the next request key in a caching proxy. ### Client ember-client shares the same parser on the response path. An upstream that sends both headers can desync a poole
org.http4s:http4s-ember-core_3
source listed>= 1.0.0-M1, <= 1.0.0-M46
## Summary Ember's HTTP/1.1 request parser does not reject a message that carries both a `Transfer-Encoding` and a `Content-Length` header. RFC 9112 §6.1 requires a server to treat such a message as a framing error and close the connection. An intermediary that follows the RFC's CL-strip-and-forward path (or that prioritises `Content-Length`) will frame the body differently from Ember, enabling HTTP request smuggling (CL.TE). ## Impact ### Server Request smuggling when ember-server is an origin behind an intermediary that forwards both headers over a keep-alive backend connection and frames by `Content-Length` while Ember frames by chunked: - Front-end security bypass: the smuggled request reaches paths the intermediary's ACL/auth layer would have blocked, with attacker-chosen method and headers. - Cross-user request hijack: a dangling smuggled prefix concatenates with the next victim's request on the shared backend socket, capturing its headers. - Cache poisoning: the smuggled response is associated with the next request key in a caching proxy. ### Client ember-client shares the same parser on the response path. An upstream that sends both headers can desync a poole
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-8h4c-x2wg-6xp8 ↗
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.