vulnerability / NVI-00015368 / Revision 1
Http4s Ember HTTP/2 does not enforce SETTINGS_MAX_CONCURRENT_STREAMS
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
An ember server with HTTP/2 enabled (`.withHttp2`) does not enforce `SETTINGS_MAX_CONCURRENT_STREAMS` on streams opened by the peer. A single unauthenticated connection can open an unbounded number of concurrent streams, each of which allocates per-stream server state that is never released, exhausting the heap. ## Impact Unauthenticated remote denial of service (memory exhaustion) against any Ember server built `.withHttp2`. This is the resource-exhaustion class of the HTTP/2 "Rapid Reset" family (CVE-2023-44487). The same unchecked allocation path is reachable on the client via server-initiated `PUSH_PROMISE` frames, so a malicious or compromised server can exhaust an ember-client's heap the same way. ## Preconditions - Server: with `.withHttp2` enabled. - Client: makes HTTP/2 requests to malicious or compromised sites. `enablePush` is not enforced. ## Workarounds - Disable HTTP/2 on `EmberServerBuilder` or `EmberClientBuilder` (default) - Client only: avoid HTTP/2 to untrusted servers until patched.
org.http4s:http4s-ember-core_2.13
source listed<= 0.23.34
An ember server with HTTP/2 enabled (`.withHttp2`) does not enforce `SETTINGS_MAX_CONCURRENT_STREAMS` on streams opened by the peer. A single unauthenticated connection can open an unbounded number of concurrent streams, each of which allocates per-stream server state that is never released, exhausting the heap. ## Impact Unauthenticated remote denial of service (memory exhaustion) against any Ember server built `.withHttp2`. This is the resource-exhaustion class of the HTTP/2 "Rapid Reset" family (CVE-2023-44487). The same unchecked allocation path is reachable on the client via server-initiated `PUSH_PROMISE` frames, so a malicious or compromised server can exhaust an ember-client's heap the same way. ## Preconditions - Server: with `.withHttp2` enabled. - Client: makes HTTP/2 requests to malicious or compromised sites. `enablePush` is not enforced. ## Workarounds - Disable HTTP/2 on `EmberServerBuilder` or `EmberClientBuilder` (default) - Client only: avoid HTTP/2 to untrusted servers until patched.
org.http4s:http4s-ember-core_3
source listed<= 0.23.34
An ember server with HTTP/2 enabled (`.withHttp2`) does not enforce `SETTINGS_MAX_CONCURRENT_STREAMS` on streams opened by the peer. A single unauthenticated connection can open an unbounded number of concurrent streams, each of which allocates per-stream server state that is never released, exhausting the heap. ## Impact Unauthenticated remote denial of service (memory exhaustion) against any Ember server built `.withHttp2`. This is the resource-exhaustion class of the HTTP/2 "Rapid Reset" family (CVE-2023-44487). The same unchecked allocation path is reachable on the client via server-initiated `PUSH_PROMISE` frames, so a malicious or compromised server can exhaust an ember-client's heap the same way. ## Preconditions - Server: with `.withHttp2` enabled. - Client: makes HTTP/2 requests to malicious or compromised sites. `enablePush` is not enforced. ## Workarounds - Disable HTTP/2 on `EmberServerBuilder` or `EmberClientBuilder` (default) - Client only: avoid HTTP/2 to untrusted servers until patched.
org.http4s:http4s-ember-core_2.13
source listed>= 1.0.0-M1, <= 1.0.0-M46
An ember server with HTTP/2 enabled (`.withHttp2`) does not enforce `SETTINGS_MAX_CONCURRENT_STREAMS` on streams opened by the peer. A single unauthenticated connection can open an unbounded number of concurrent streams, each of which allocates per-stream server state that is never released, exhausting the heap. ## Impact Unauthenticated remote denial of service (memory exhaustion) against any Ember server built `.withHttp2`. This is the resource-exhaustion class of the HTTP/2 "Rapid Reset" family (CVE-2023-44487). The same unchecked allocation path is reachable on the client via server-initiated `PUSH_PROMISE` frames, so a malicious or compromised server can exhaust an ember-client's heap the same way. ## Preconditions - Server: with `.withHttp2` enabled. - Client: makes HTTP/2 requests to malicious or compromised sites. `enablePush` is not enforced. ## Workarounds - Disable HTTP/2 on `EmberServerBuilder` or `EmberClientBuilder` (default) - Client only: avoid HTTP/2 to untrusted servers until patched.
org.http4s:http4s-ember-core_3
source listed>= 1.0.0-M1, <= 1.0.0-M46
An ember server with HTTP/2 enabled (`.withHttp2`) does not enforce `SETTINGS_MAX_CONCURRENT_STREAMS` on streams opened by the peer. A single unauthenticated connection can open an unbounded number of concurrent streams, each of which allocates per-stream server state that is never released, exhausting the heap. ## Impact Unauthenticated remote denial of service (memory exhaustion) against any Ember server built `.withHttp2`. This is the resource-exhaustion class of the HTTP/2 "Rapid Reset" family (CVE-2023-44487). The same unchecked allocation path is reachable on the client via server-initiated `PUSH_PROMISE` frames, so a malicious or compromised server can exhaust an ember-client's heap the same way. ## Preconditions - Server: with `.withHttp2` enabled. - Client: makes HTTP/2 requests to malicious or compromised sites. `enablePush` is not enforced. ## Workarounds - Disable HTTP/2 on `EmberServerBuilder` or `EmberClientBuilder` (default) - Client only: avoid HTTP/2 to untrusted servers until patched.
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-9vwc-pc8p-253q ↗
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.