BarnOwl before 1.6.2 does not check the return code of calls to the (1) ZPending and (2) ZReceiveNotice functions in libzephyr, which allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via unknown vectors.

Buffer overflow in BarnOwl before 1.5.1 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted CC: header.

Multiple buffer overflows in (a) BarnOwl before 1.0.5 and (b) owl 2.1.11 allow remote attackers to execute arbitrary code via vectors involving (1) a crafted zcrypt message, related to zcrypt.c; (2) a reply command on a message with a Zephyr Cc: list, related to zwrite.c; and unspecified other use of the products.