An openssl1.0 security update has been released for Debian GNU/Linux 9 LTS to address multiple security issues.

DLA 2378-1: openssl1.0 security update

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Debian LTS Advisory DLA-2378-1 debian-lts@lists.debian.org
  https://www.debian.org/lts/security/ Roberto C. Sánchez
September 25, 2020   https://wiki.debian.org/LTS
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Package : openssl1.0
Version : 1.0.2u-1~deb9u2
CVE ID : CVE-2020-1968

Robert Merget, Marcus Brinkmann, Nimrod Aviram, and Juraj Somorovsky
discovered that certain Diffie-Hellman ciphersuites in the TLS
specification and implemented by OpenSSL contained a flaw. A remote
attacker could possibly use this issue to eavesdrop on encrypted
communications. This was fixed in this update by disabling the insecure
ciphersuites.

For Debian 9 stretch, this problem has been fixed in version
1.0.2u-1~deb9u2.

We recommend that you upgrade your openssl1.0 packages.

For the detailed security status of openssl1.0 please refer to
its security tracker page at:
  https://security-tracker.debian.org/tracker/openssl1.0

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