QID 982952

QID 982952: Java (maven) Security Update for org.http4s:http4s-blaze-server_2.13 (GHSA-xhv5-w9c5-2r2w)

Security update has been released for org.http4s:http4s-blaze-server_2.12,org.http4s:http4s-blaze-server_2.13 to fix the vulnerability.

Note: The preceding description block is extracted directly from the security advisory. Using automation, we have attempted to clean and format it as much as possible without introducing additional issues.

blaze-core, a library underlying http4s-blaze-server, accepts connections unboundedly on its selector pool. This has the net effect of amplifying degradation in services that are unable to handle their current request load, since incoming connections are still accepted and added to an unbounded queue. Each connection allocates a socket handle, which drains a scarce OS resource. This can also confound higher level circuit breakers which work based on detecting failed connections.

http4s provides a general `MaxActiveRequests` middleware mechanism for limiting open connections, but it is enforced inside the Blaze accept loop, after the connection is accepted and the socket opened. Thus, the limit only prevents the number of connections which can be simultaneously processed, not the number of connections which can be held open.

CVSS V3 rated as High - 7.5 severity.

CVSS V2 rated as Medium - 5 severity.

Solution

In 0.21.18, 0.22.0-M3, and 1.0.0-M16, a new`maxConnections` property, with a default value of 1024, has been added to the `BlazeServerBuilder`. Setting the value to a negative number restores unbounded behavior, but is strongly disrecommended.

The NIO2 backend does not respect `maxConnections`. Its use is now deprecated in http4s-0.21, and the option is removed altogether starting in http4s-0.22.

The connections are bounded in 0.21.17, 0.22.0-M2, and 1.0.0-M14, but the `maxConnections` parameter was passed incorrectly, making it impossible to change the Blaze default of 512.Workaround:
* An Nginx side-car acting as a reverse proxy for the local http4s-blaze-server instance would be able to apply a connection limiting semantic before the sockets reach blaze-core. Nginxs connection bounding is both asynchronous and properly respects backpressure.
* http4s-ember-server is an alternative to http4s-blaze-server, but does not yet have HTTP/2 or web socket support. Its performance in terms of RPS is appreciably behind Blazes, and as the newest backend, has substantially less industrial uptake.
* http4s-jetty is an alternative to http4s-blaze-server, but does not yet have web socket support. Its performance in terms of requests per second is somewhat behind Blazes, and despite Jetty's industrial adoption, the http4s integration has substantially less industrial uptake.
* http4s-tomcat is an alternative to http4s-blaze-server, but does not yet have HTTP/2 web socket support. Its performance in terms of requests per second is somewhat behind Blazes, and despite Jetty's industrial adoption, the http4s integration has substantially less industrial uptake.

Vendor References

GHSA-xhv5-w9c5-2r2w - github.com/advisories/GHSA-xhv5-w9c5-2r2w

CVEs related to QID 982952

CVE-2021-21294 |

Software Advisories

Advisory ID	Software	Component	Link
GHSA-xhv5-w9c5-2r2w	org.http4s:http4s-blaze-server_2.12		github.com/advisories/GHSA-xhv5-w9c5-2r2w
GHSA-xhv5-w9c5-2r2w	org.http4s:http4s-blaze-server_2.13		github.com/advisories/GHSA-xhv5-w9c5-2r2w

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