Phusion · Phusion Passenger · CVE-2015-7519
**Name of the Vulnerable Software and Affected Versions**
Phusion Passenger versions prior to 4.0.60
Phusion Passenger versions 5.0.x prior to 5.0.22
**Description**
The issue allows remote attackers to spoof headers passed to applications by using an (underscore) character instead of a - (dash) character in an HTTP header. This can be demonstrated by an X User header. The problem occurs when Phusion Passenger is used in Apache integration mode or in standalone mode without a filtering proxy.
**Recommendations**
For Phusion Passenger versions prior to 4.0.60, update to version 4.0.60 or later.
For Phusion Passenger versions 5.0.x prior to 5.0.22, update to version 5.0.22 or later.