### Summary Netty HTTP/2 max header size handling produces attack similar to HTTP/2 Rapid Reset. ### Details There is a setting in the http2 specification called `SETTINGS_MAX_HEADER_LIST_SIZE`. According to[ the RFC](https://www.rfc-editor.org/rfc/rfc9113.html#name-defined-settings): “This advisory setting informs a peer of the maximum field section size that the sender is prepared to accept, in units of octets.” When a client sends that setting to Netty, it appears that Netty will behave as follows: - Read the request - Proxy the request to the origin - Attempt to produce a response - Create an exception while writing the headers for the response Functionally, this should be similar to the http2 reset attack, but with a different on-the-wire signature. ## Remediation When speaking with clients, Netty should potentially treat this as “advisory” and ignore it. It would be best to ignore the SETTINGS_MAX_HEADER_LIST_SIZE setting from clients (or ignore it when sending to clients). According to the spec, a server does not need to honor this advisory setting, and it appears that other http/2 implementations ignore it when acting as a server. ### Impact This is a DDoS attack similar to the HTTP/2 Rapid Reset Attack. ## Credit Jonathan Looney (Engineering, Netflix) ## Contact Ashley Tolbert (Security, Netflix) - [email protected]
### Summary Netty HTTP/2 max header size handling produces attack similar to HTTP/2 Rapid Reset. ### Details There is a setting in the http2 specification called `SETTINGS_MAX_HEADER_LIST_SIZE`. According to[ the RFC](https://www.rfc-editor.org/rfc/rfc9113.html#name-defined-settings): “This advisory setting informs a peer of the maximum field section size that the sender is prepared to accept, in units of octets.” When a client sends that setting to Netty, it appears that Netty will behave as follows: - Read the request - Proxy the request to the origin - Attempt to produce a response - Create an exception while writing the headers for the response Functionally, this should be similar to the http2 reset attack, but with a different on-the-wire signature. ## Remediation When speaking with clients, Netty should potentially treat this as “advisory” and ignore it. It would be best to ignore the SETTINGS_MAX_HEADER_LIST_SIZE setting from clients (or ignore it when sending to clients). According to the spec, a server does not need to honor this advisory setting, and it appears that other http/2 implementations ignore it when acting as a server. ### Impact This is a DDoS attack similar to the HTTP/2 Rapid Reset Attack. ## Credit Jonathan Looney (Engineering, Netflix) ## Contact Ashley Tolbert (Security, Netflix) - [email protected]
Update io.netty:netty-codec-http2 to 4.2.15.Final; io.netty:netty-codec-http2 to 4.1.135.Final if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanNetty susceptible to HTTP/2 Reset Attack with different on-the-wire signature affects io.netty:netty-codec-http2 (maven), io.netty:netty-codec-http2 (maven). Severity is medium. ### Summary Netty HTTP/2 max header size handling produces attack similar to HTTP/2 Rapid Reset. ### Details There is a setting in the http2 specification called `SETTINGS_MAX_HEADER_LIST_SIZE`. According to[ the RFC](https://www.rfc-editor.org/rfc/rfc9113.html#name-defined-settings): “This advisory setting informs a peer of the maximum field section size that the sender is prepared to accept, in units of octets.” When a client sends that setting to Netty, it appears that Netty will behave as follows: - Read the request - Proxy the request to the origin - Attempt to produce a response - Create an exception while writing the headers for the response Functionally, this should be similar to the http2 reset attack, but with a different on-the-wire signature. ## Remediation When speaking with clients, Netty should potentially treat this as “advisory” and ignore it. It would be best to ignore the SETTINGS_MAX_HEADER_LIST_SIZE setting from clients (or ignore it when sending to clients). According to the spec, a server does not need to honor this advisory setting, and it appears that other http/2 implementations ignore it when acting as a server. ### Impact This is a DDoS attack similar to the HTTP/2 Rapid Reset Attack. ## Credit Jonathan Looney (Engineering, Netflix) ## Contact Ashley Tolbert (Security, Netflix) - [email protected]
AI coding agents often install or upgrade packages automatically in maven. A medium vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| io.netty:netty-codec-http2maven | >=4.2.0.Final,<=4.2.14.Final | 4.2.15.Final |
| io.netty:netty-codec-http2maven | <=4.1.134.Final | 4.1.135.Final |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUpdate io.netty:netty-codec-http2 to 4.2.15.Final; io.netty:netty-codec-http2 to 4.1.135.Final if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanNetty susceptible to HTTP/2 Reset Attack with different on-the-wire signature affects io.netty:netty-codec-http2 (maven), io.netty:netty-codec-http2 (maven). Severity is medium. ### Summary Netty HTTP/2 max header size handling produces attack similar to HTTP/2 Rapid Reset. ### Details There is a setting in the http2 specification called `SETTINGS_MAX_HEADER_LIST_SIZE`. According to[ the RFC](https://www.rfc-editor.org/rfc/rfc9113.html#name-defined-settings): “This advisory setting informs a peer of the maximum field section size that the sender is prepared to accept, in units of octets.” When a client sends that setting to Netty, it appears that Netty will behave as follows: - Read the request - Proxy the request to the origin - Attempt to produce a response - Create an exception while writing the headers for the response Functionally, this should be similar to the http2 reset attack, but with a different on-the-wire signature. ## Remediation When speaking with clients, Netty should potentially treat this as “advisory” and ignore it. It would be best to ignore the SETTINGS_MAX_HEADER_LIST_SIZE setting from clients (or ignore it when sending to clients). According to the spec, a server does not need to honor this advisory setting, and it appears that other http/2 implementations ignore it when acting as a server. ### Impact This is a DDoS attack similar to the HTTP/2 Rapid Reset Attack. ## Credit Jonathan Looney (Engineering, Netflix) ## Contact Ashley Tolbert (Security, Netflix) - [email protected]
AI coding agents often install or upgrade packages automatically in maven. A medium vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| io.netty:netty-codec-http2maven | >=4.2.0.Final,<=4.2.14.Final | 4.2.15.Final |
| io.netty:netty-codec-http2maven | <=4.1.134.Final | 4.1.135.Final |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard