mod_headers CVE-2013-5704

If you must use the mod, it looks like a good work around until this is fixed, is to install Ondřej Surý PPA for Apache2.x. The PPA has apache 2.4.12 for ubuntu trusty and other versions.
https://launchpad.net/~ondrej/+archive/ubuntu/apache2
I have been running 2.4.12 for a few days now on trusty with no issues and the PCI scanners are happy.

This bug was fixed in the package apache2 - 2.4.10-1ubuntu1.1

---------------
apache2 (2.4.10-1ubuntu1.1) utopic-security; urgency=medium

  * SECURITY UPDATE: HTTP header replacement via HTTP trailers (LP: #1425141)
    - debian/patches/CVE-2013-5704.patch: don't merge trailers by default
      and add a "MergeTrailers" directive to revert to previous behaviour
      to include/http_core.h, include/httpd.h, modules/http/http_filters.c,
      modules/http/http_request.c, modules/loggers/mod_log_config.c,
      modules/proxy/mod_proxy_http.c, server/core.c, server/protocol.c.
    - CVE-2013-5704
  * SECURITY UPDATE: mod_cache denial of service via empty HTTP
    Content-Type header
    - debian/patches/CVE-2014-3581.patch: check for NULL in
      modules/cache/cache_util.c.
    - CVE-2014-3581
  * SECURITY UPDATE: mod_proxy_fcgi deial of service via long response
    headers
    - debian/patches/CVE-2014-3583.patch: properly handle length in
      modules/aaa/mod_authnz_fcgi.c, modules/proxy/mod_proxy_fcgi.c.
    - CVE-2014-3583
  * SECURITY UPDATE: restriction bypass in mod_lua via multiple Require
    directives
    - debian/patches/CVE-2014-8109.patch: handle multiple Require
      directives with different arguments in modules/lua/mod_lua.c.
    - CVE-2014-8109
  * SECURITY UPDATE: denial of service in mod_lua via websockets PING
    - debian/patches/CVE-2015-0228.patch: fix logic in
      modules/lua/lua_request.c.
    - CVE-2015-0228
 -- Marc Deslauriers <email address hidden> Thu, 05 Mar 2015 12:05:47 -0500

This bug was fixed in the package apache2 - 2.2.14-5ubuntu8.15

---------------
apache2 (2.2.14-5ubuntu8.15) lucid-security; urgency=medium

  * SECURITY UPDATE: HTTP header replacement via HTTP trailers (LP: #1425141)
    - debian/patches/CVE-2013-5704.dpatch: don't merge trailers by default
      and add a "MergeTrailers" directive to revert to previous behaviour
      to include/http_core.h, include/httpd.h, modules/http/http_filters.c,
      modules/http/http_request.c, modules/loggers/mod_log_config.c,
      modules/proxy/mod_proxy_http.c, modules/proxy/proxy_util.c,
      server/core.c, server/protocol.c.
    - CVE-2013-5704
 -- Marc Deslauriers <email address hidden> Thu, 05 Mar 2015 12:45:09 -0500

This bug was fixed in the package apache2 - 2.4.7-1ubuntu4.4

---------------
apache2 (2.4.7-1ubuntu4.4) trusty-security; urgency=medium

  * SECURITY UPDATE: HTTP header replacement via HTTP trailers (LP: #1425141)
    - debian/patches/CVE-2013-5704.patch: don't merge trailers by default
      and add a "MergeTrailers" directive to revert to previous behaviour
      to include/http_core.h, include/httpd.h, modules/http/http_filters.c,
      modules/http/http_request.c, modules/loggers/mod_log_config.c,
      modules/proxy/mod_proxy_http.c, server/core.c, server/protocol.c.
    - CVE-2013-5704
  * SECURITY UPDATE: mod_cache denial of service via empty HTTP
    Content-Type header
    - debian/patches/CVE-2014-3581.patch: check for NULL in
      modules/cache/cache_util.c.
    - CVE-2014-3581
 -- Marc Deslauriers <email address hidden> Tue, 10 Mar 2015 07:42:50 -0400

This bug was fixed in the package apache2 - 2.2.22-1ubuntu1.8

---------------
apache2 (2.2.22-1ubuntu1.8) precise-security; urgency=medium

  * SECURITY UPDATE: HTTP header replacement via HTTP trailers (LP: #1425141)
    - debian/patches/CVE-2013-5704.patch: don't merge trailers by default
      and add a "MergeTrailers" directive to revert to previous behaviour
      to include/http_core.h, include/httpd.h, modules/http/http_filters.c,
      modules/http/http_request.c, modules/loggers/mod_log_config.c,
      modules/proxy/mod_proxy_http.c, modules/proxy/proxy_util.c,
      server/core.c, server/protocol.c.
    - CVE-2013-5704
 -- Marc Deslauriers <email address hidden> Thu, 05 Mar 2015 12:40:00 -0500