PostgreSQL before 8.3.7, 8.2.13, 8.1.17, 8.0.21, and 7.4.25 allows remote authenticated users to cause a denial of service (stack consumption and crash) by triggering a failure in the conversion of a localized error message to a client-specified encoding, as demonstrated using mismatched encoding conversion requests.
"PostgreSQL allows remote authenticated users to cause a momentary denial
of service (crash due to stack consumption) when there is a failure to
convert a localized error message to the client-specified encoding.
In releases 8.3.6, 8.2.12, 8.1.16. 8.0.20, and 7.4.24, a trivial
misconfiguration is sufficient to provoke a crash. In older releases
it is necessary to select a locale and client encoding for which
specific messages fail to translate, and so a given installation may or
may not be vulnerable depending on the administrator-determined locale
Releases 8.3.7, 8.2.13, 8.1.17, 8.0.21, and 7.4.25 are secure against
all known variants of this issue."