Eudora before 6.1.1 allows remote attackers to cause a denial of service (crash) via an e-mail with a long "To:" field, possibly due to a buffer overflow.
Eudora email client 5.1.1, with "use Microsoft viewer" enabled, allows remote attackers to execute arbitrary programs via an HTML email message containing a META refresh tag that references an embedded .mhtml file with ActiveX controls that execute a second embedded program, which is processed by Internet Explorer.
Qualcomm Eudora 5.1.1, 5.2, and possibly other versions stores email attachments in a predictable location, which allows remote attackers to read arbitrary files via a link that loads an attachment with malicious script into a frame, which then executes the script in the local browser context.
Buffer overflow in Eudora 5.1.1 and 5.0-J for Windows, and possibly other versions, allows remote attackers to execute arbitrary code via a multi-part message with a long boundary string.