A netty security update has been released for Debian GNU/Linux 9 LTS to address several vulnerabilities.

DLA 2364-1: netty security update

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Debian LTS Advisory DLA-2364-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Roberto C. Sánchez
September 04, 2020   https://wiki.debian.org/LTS
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Package : netty
Version : 1:4.1.7-2+deb9u2
CVE ID : CVE-2019-20444 CVE-2019-20445 CVE-2020-7238 CVE-2020-11612
Debian Bug : 950966 950967

Several vulnerabilities have been discovered in netty, a Java NIO
client/server socket framework.

CVE-2019-20444

HttpObjectDecoder.java in Netty before 4.1.44 allows an HTTP header
that lacks a colon, which might be interpreted as a separate header
with an incorrect syntax, or might be interpreted as an "invalid
fold."

CVE-2019-20445

HttpObjectDecoder.java in Netty before 4.1.44 allows a Content-Length
header to be accompanied by a second Content-Length header, or by a
Transfer-Encoding header.

CVE-2020-7238

Netty 4.1.43.Final allows HTTP Request Smuggling because it
mishandles Transfer-Encoding whitespace (such as a
[space]Transfer-Encoding:chunked line) and a later Content-Length
header. This issue exists because of an incomplete fix for
CVE-2019-16869.

CVE-2020-11612

The ZlibDecoders in Netty 4.1.x before 4.1.46 allow for unbounded
memory allocation while decoding a ZlibEncoded byte stream. An
attacker could send a large ZlibEncoded byte stream to the Netty
server, forcing the server to allocate all of its free memory to a
single decoder.

For Debian 9 stretch, these problems have been fixed in version
1:4.1.7-2+deb9u2.

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

Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://wiki.debian.org/LTS