Hashcash: Possible heap overflow

Background

Hashcash is a utility for generating Hashcash tokens, a proof-of-work system to reduce the impact of spam.

Description

Andreas Seltenreich has reported a possible heap overflow in the array_push() function in hashcash.c, as a result of an incorrect amount of allocated memory for the “ARRAY” structure.

Impact

By sending malicious entries to the Hashcash utility, an attacker may be able to cause an overflow, potentially resulting in the execution of arbitrary code with the privileges of the user running the application.

Workaround

There is no known workaround at this time.

Resolution

All Hashcash users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-misc/hashcash-1.21"