MEDIUM
In dnsmasq before 2.78, if the DNS packet size does not match the expected size, the size parameter in a memset call gets a negative value. As it is an unsigned value, memset ends up writing up to 0xffffffff zero's (0xffffffffffffffff in 64 bit platforms), making dnsmasq crash.
http://thekelleys.org.uk/dnsmasq/CHANGELOG
http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=63437ffbb58837b214b4b92cb1c54bc5f3279928
http://www.securityfocus.com/bid/101085
http://www.securityfocus.com/bid/101977
http://www.securitytracker.com/id/1039474
https://access.redhat.com/security/vulnerabilities/3199382
https://cert-portal.siemens.com/productcert/pdf/ssa-689071.pdf
https://security.googleblog.com/2017/10/behind-masq-yet-more-dns-and-dhcp.html
https://www.mail-archive.com/[email protected]/msg11664.html
https://www.mail-archive.com/[email protected]/msg11665.html
https://www.synology.com/support/security/Synology_SA_17_59_Dnsmasq
Source: MITRE
Published: 2017-10-03
Updated: 2018-05-11
Type: CWE-20
Base Score: 5
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P
Impact Score: 2.9
Exploitability Score: 10
Severity: MEDIUM
Base Score: 7.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 3.9
Severity: HIGH