Debian Security Advisory

DLA-507-1 nss -- LTS security update

Date Reported:
07 Jun 2016
Affected Packages:
Security database references:
In Mitre's CVE dictionary: CVE-2015-4000.
More information:

A vulnerability has been found in nss.

  • CVE-2015-4000

    With TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabled on a server but not on a client, does not properly convey a DHE_EXPORT choice, which allows man-in-the-middle attackers to conduct cipher-downgrade attacks by rewriting a ClientHello with DHE replaced by DHE_EXPORT and then rewriting a ServerHello with DHE_EXPORT replaced by DHE, aka the Logjam issue.

    The solution in nss was to not accept bit lengths less than 1024. This may potentially be a backwards incompatibility issue but such low bit lengths should not be in use so it was deemed acceptable.

For Debian 7 Wheezy, these problems have been fixed in version 2:3.14.5-1+deb7u7.

We recommend that you upgrade your nss packages.

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