USN-2672-1: NSS vulnerabilities

Releases

• Ubuntu 15.04
• Ubuntu 14.10
• Ubuntu 14.04 ESM
• Ubuntu 12.04

Packages

• nss - Network Security Service library

Details

Karthikeyan Bhargavan discovered that NSS incorrectly handled state
transitions for the TLS state machine. If a remote attacker were able to
perform a machine-in-the-middle attack, this flaw could be exploited to skip
the ServerKeyExchange message and remove the forward-secrecy property.
(CVE-2015-2721)

Watson Ladd discovered that NSS incorrectly handled Elliptical Curve
Cryptography (ECC) multiplication. A remote attacker could possibly use
this issue to spoof ECDSA signatures. (CVE-2015-2730)

As a security improvement, this update modifies NSS behaviour to reject DH
key sizes below 768 bits, preventing a possible downgrade attack.

This update also refreshes the NSS package to version 3.19.2 which includes
the latest CA certificate bundle.

Update instructions

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

Ubuntu 15.04

• libnss3 - 2:3.19.2-0ubuntu15.04.1

Ubuntu 14.10

• libnss3 - 2:3.19.2-0ubuntu0.14.10.1

Ubuntu 14.04

• libnss3 - 2:3.19.2-0ubuntu0.14.04.1

Ubuntu 12.04

• libnss3 - 3.19.2-0ubuntu0.12.04.1

This update uses a new upstream release, which includes additional bug
fixes. After a standard system update you need to restart any applications
that use NSS, such as Evolution and Chromium, to make all the necessary
changes.

References

• CVE-2015-2721
• CVE-2015-2730

Related notices

• USN-2673-1
• USN-2656-1
• USN-2656-2