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Ubuntu Security Notice USN-6663-2
March 13, 2024

openssl update
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 16.04 LTS (Available with Ubuntu Pro)

Summary:

Add implicit rejection in PKCS#1 v1.5 in OpenSSL.

Software Description:
- openssl: Secure Socket Layer (SSL) cryptographic library and tools

Details:

USN-6663-1 provided a security update for OpenSSL.
This update provides the corresponding update for
Ubuntu 16.04 LTS.

Original advisory details:

  As a security improvement, this update prevents OpenSSL
  from returning an error when detecting wrong padding
  in PKCS#1 v1.5 RSA, to prevent its use in possible
  Bleichenbacher timing attacks.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 16.04 LTS (Available with Ubuntu Pro):
   libssl-doc                      1.0.2g-1ubuntu4.20+esm12
   libssl1.0.0                     1.0.2g-1ubuntu4.20+esm12
   openssl                         1.0.2g-1ubuntu4.20+esm12

After a standard system update you need to reboot your computer to make
all the necessary changes.

References:
   https://ubuntu.com/security/notices/USN-6663-2
   https://ubuntu.com/security/notices/USN-6663-1
   https://launchpad.net/bugs/2054090