An OpenSSL security update has been released for Ubuntu Linux 18.04 LTS, 20.04 LTS, and 20.10.

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Ubuntu Security Notice USN-4891-1
March 25, 2021

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

- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

OpenSSL could be made to crash or run programs if it received specially
crafted network traffic.

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

Details:

It was discovered that OpenSSL incorrectly handled certain renegotiation
ClientHello messages. A remote attacker could use this issue to cause
OpenSSL to crash, resulting in a denial of service, or possibly execute
arbitrary code.

Update instructions:

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

Ubuntu 20.10:
libssl1.1 1.1.1f-1ubuntu4.3

Ubuntu 20.04 LTS:
libssl1.1 1.1.1f-1ubuntu2.3

Ubuntu 18.04 LTS:
libssl1.1 1.1.1-1ubuntu2.1~18.04.9

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

References:
  https://ubuntu.com/security/notices/USN-4891-1
CVE-2021-3449

Package Information:
  https://launchpad.net/ubuntu/+source/openssl/1.1.1f-1ubuntu4.3
  https://launchpad.net/ubuntu/+source/openssl/1.1.1f-1ubuntu2.3
  https://launchpad.net/ubuntu/+source/openssl/1.1.1-1ubuntu2.1~18.04.9