The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to cause a denial of service (infinite loop and stack exhaustion) via vectors involving BDAT commands and an improper check for a '.' character signifying the end of the content, related to the bdat_getc function.

References

• https://nvd.nist.gov/vuln/detail/CVE-2017-16944
• https://bugs.exim.org/show_bug.cgi?id=2201
• https://lists.exim.org/lurker/message/20171125.034842.d1d75cac.en.html
• https://www.debian.org/security/2017/dsa-4053
• https://www.exploit-db.com/exploits/43184/
• http://openwall.com/lists/oss-security/2017/11/25/1
• http://openwall.com/lists/oss-security/2017/11/25/2
• http://openwall.com/lists/oss-security/2017/11/25/3
• http://www.openwall.com/lists/oss-security/2021/05/04/7
• http://www.securitytracker.com/id/1039873