Debian Security Advisory

DLA-2761-1 openssl1.0 -- LTS security update

Date Reported:
18 Sep 2021
Affected Packages:
Security database references:
No other external database security references currently available.
More information:

The legacy 1.0 version of OpenSSL, a cryptography library for secure communication, fails to validate alternate trust chains in some conditions. In particular this breaks connecting to servers that use Let's Encrypt certificates, starting 2021-10-01.

For Debian 9 stretch, this problem has been fixed in version 1.0.2u-1~deb9u5.

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:

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