vulnerability / NVI-00017860 / Revision 1
Http4s Ember HTTP/2: unbounded continuation frame accumulation
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.
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.
org.http4s:http4s-ember-core_2.12
source listed<= 0.23.34
When Ember receives an HTTP/2 `HEADERS` or `PUSH_PROMISE` frame without the `END_HEADERS` flag, it buffers the header block fragment and waits for subsequent `CONTINUATION` frames. These accumulate unbounded until the connection closes. ### Impact A remote, unauthenticated peer can exhaust the heap on any Ember endpoint that has HTTP/2 enabled: - **ember-server with `.withHttp2`**: any HTTP/2 client can trigger this against any reachable path (including paths that return 404). No authentication is required because the attack completes before the request is decoded. - **ember-client with `.withHttp2`**: a malicious or compromised origin server can trigger this via the response header block. A single in-flight request is sufficient. Memory consumption is bounded only by the attacker's upload bandwidth and the connection lifetime. ### Prerequisites - `EmberServerBuilder` configured with `.withHttp2`. - For the server: the attacker can establish an HTTP/2 connection - For the client: the application makes a request to an attacker-controlled origin. HTTP/2 incoming headers exceeding the configured size limit are buffer in order to generate an informative HTTP 413 resp
org.http4s:http4s-ember-core_2.13
source listed<= 0.23.34
When Ember receives an HTTP/2 `HEADERS` or `PUSH_PROMISE` frame without the `END_HEADERS` flag, it buffers the header block fragment and waits for subsequent `CONTINUATION` frames. These accumulate unbounded until the connection closes. ### Impact A remote, unauthenticated peer can exhaust the heap on any Ember endpoint that has HTTP/2 enabled: - **ember-server with `.withHttp2`**: any HTTP/2 client can trigger this against any reachable path (including paths that return 404). No authentication is required because the attack completes before the request is decoded. - **ember-client with `.withHttp2`**: a malicious or compromised origin server can trigger this via the response header block. A single in-flight request is sufficient. Memory consumption is bounded only by the attacker's upload bandwidth and the connection lifetime. ### Prerequisites - `EmberServerBuilder` configured with `.withHttp2`. - For the server: the attacker can establish an HTTP/2 connection - For the client: the application makes a request to an attacker-controlled origin. HTTP/2 incoming headers exceeding the configured size limit are buffer in order to generate an informative HTTP 413 resp
org.http4s:http4s-ember-core_3
source listed<= 0.23.34
When Ember receives an HTTP/2 `HEADERS` or `PUSH_PROMISE` frame without the `END_HEADERS` flag, it buffers the header block fragment and waits for subsequent `CONTINUATION` frames. These accumulate unbounded until the connection closes. ### Impact A remote, unauthenticated peer can exhaust the heap on any Ember endpoint that has HTTP/2 enabled: - **ember-server with `.withHttp2`**: any HTTP/2 client can trigger this against any reachable path (including paths that return 404). No authentication is required because the attack completes before the request is decoded. - **ember-client with `.withHttp2`**: a malicious or compromised origin server can trigger this via the response header block. A single in-flight request is sufficient. Memory consumption is bounded only by the attacker's upload bandwidth and the connection lifetime. ### Prerequisites - `EmberServerBuilder` configured with `.withHttp2`. - For the server: the attacker can establish an HTTP/2 connection - For the client: the application makes a request to an attacker-controlled origin. HTTP/2 incoming headers exceeding the configured size limit are buffer in order to generate an informative HTTP 413 resp
org.http4s:http4s-ember-core_2.13
source listed>= 1.0.0-M1, <= 1.0.0-M46
When Ember receives an HTTP/2 `HEADERS` or `PUSH_PROMISE` frame without the `END_HEADERS` flag, it buffers the header block fragment and waits for subsequent `CONTINUATION` frames. These accumulate unbounded until the connection closes. ### Impact A remote, unauthenticated peer can exhaust the heap on any Ember endpoint that has HTTP/2 enabled: - **ember-server with `.withHttp2`**: any HTTP/2 client can trigger this against any reachable path (including paths that return 404). No authentication is required because the attack completes before the request is decoded. - **ember-client with `.withHttp2`**: a malicious or compromised origin server can trigger this via the response header block. A single in-flight request is sufficient. Memory consumption is bounded only by the attacker's upload bandwidth and the connection lifetime. ### Prerequisites - `EmberServerBuilder` configured with `.withHttp2`. - For the server: the attacker can establish an HTTP/2 connection - For the client: the application makes a request to an attacker-controlled origin. HTTP/2 incoming headers exceeding the configured size limit are buffer in order to generate an informative HTTP 413 resp
org.http4s:http4s-ember-core_3
source listed>= 1.0.0-M1, <= 1.0.0-M46
When Ember receives an HTTP/2 `HEADERS` or `PUSH_PROMISE` frame without the `END_HEADERS` flag, it buffers the header block fragment and waits for subsequent `CONTINUATION` frames. These accumulate unbounded until the connection closes. ### Impact A remote, unauthenticated peer can exhaust the heap on any Ember endpoint that has HTTP/2 enabled: - **ember-server with `.withHttp2`**: any HTTP/2 client can trigger this against any reachable path (including paths that return 404). No authentication is required because the attack completes before the request is decoded. - **ember-client with `.withHttp2`**: a malicious or compromised origin server can trigger this via the response header block. A single in-flight request is sufficient. Memory consumption is bounded only by the attacker's upload bandwidth and the connection lifetime. ### Prerequisites - `EmberServerBuilder` configured with `.withHttp2`. - For the server: the attacker can establish an HTTP/2 connection - For the client: the application makes a request to an attacker-controlled origin. HTTP/2 incoming headers exceeding the configured size limit are buffer in order to generate an informative HTTP 413 resp
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-cp4q-fqw9-4hf6 ↗
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.