A Nettle security update has been released for Ubuntu Linux 18.04 LTS, 20.04 LTS, 20.10, and 21.04.

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Ubuntu Security Notice USN-4990-1
June 17, 2021

nettle vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 21.04
- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in Nettle.

Software Description:
- nettle: low level cryptographic library

Details:

It was discovered that Nettle incorrectly handled RSA decryption. A remote
attacker could possibly use this issue to cause Nettle to crash, resulting
in a denial of service. (CVE-2021-3580)

It was discovered that Nettle incorrectly handled certain padding oracles.
A remote attacker could possibly use this issue to perform a variant of the
Bleichenbacher attack. This issue only affected Ubuntu 18.04 LTS.
(CVE-2018-16869)

Update instructions:

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

Ubuntu 21.04:
libnettle8 3.7-2.1ubuntu1.1

Ubuntu 20.10:
libnettle8 3.6-2ubuntu0.2

Ubuntu 20.04 LTS:
libnettle7 3.5.1+really3.5.1-2ubuntu0.2

Ubuntu 18.04 LTS:
libnettle6 3.4.1-0ubuntu0.18.04.1

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-4990-1
CVE-2018-16869, CVE-2021-3580

Package Information:
  https://launchpad.net/ubuntu/+source/nettle/3.7-2.1ubuntu1.1
  https://launchpad.net/ubuntu/+source/nettle/3.6-2ubuntu0.2
  https://launchpad.net/ubuntu/+source/nettle/3.5.1+really3.5.1-2ubuntu0.2
  https://launchpad.net/ubuntu/+source/nettle/3.4.1-0ubuntu0.18.04.1

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