There are some (as of yet unknown) scenario's where pluto receives a kernel ACQUIRE for which it already detects it has a valid STATE object. Thus, it interprets these as a "duplicate acquire" and no action is taken. However, the state found does not belong to a valid IPsec SA, and so the tunnel is down and cannot be started because it is deemed up based on the "duplicate" check.
When this happens, packets are dropped for a lack of IPsec SA - or leaked in the clear, depending on whether this was a "private" or "private-or-clear" group state.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (libreswan bug fix and enhancement update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.