It was reported that Netty, a Java NIO client/server framework, is prone to a HTTP request smuggling vulnerability due to mishandling whitespace before the colon in HTTP headers.

For the oldstable distribution (stretch), this problem has been fixed in version 1:4.1.7-2+deb9u1.

For the stable distribution (buster), this problem has been fixed in version 1:4.1.33-1+deb10u1.

We recommend that you upgrade your netty packages.

For the detailed security status of netty please refer to its security tracker page at: https://security-tracker.debian.org/tracker/netty