Thierry Carrez of the Openstack project reports:

Title: Swift TempURL timing attack
Reporter: Samuel Merritt (SwiftStack)
Products: Swift
Affects: All supported versions

Description:
Samuel Merritt from SwiftStack reported a timing attack vulnerability in
Swift TempURL middleware. By analyzing response times to arbitrary
TempURL requests, an attacker may be able to guess valid secret URLs and
get access to objects that were only intended to be publicly shared with
specific recipients. In order to use this attack, the attacker needs to
know the targeted object name, and the object account needs to have a
TempURL key set. Only Swift setups enabling the TempURL middleware are
affected.