CVE-2020-25682

NameCVE-2020-25682
DescriptionA flaw was found in dnsmasq before 2.83. A buffer overflow vulnerability was discovered in the way dnsmasq extract names from DNS packets before validating them with DNSSEC data. An attacker on the network, who can create valid DNS replies, could use this flaw to cause an overflow with arbitrary data in a heap-allocated memory, possibly executing code on the machine. The flaw is in the rfc1035.c:extract_name() function, which writes data to the memory pointed by name assuming MAXDNAME*2 bytes are available in the buffer. However, in some code execution paths, it is possible extract_name() gets passed an offset from the base buffer, thus reducing, in practice, the number of available bytes that can be written in the buffer. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-2604-1, DSA-4844-1, ELA-389-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
dnsmasq (PTS)jessie, jessie (lts)2.72-3+deb8u7fixed
stretch (security)2.76-5+deb9u3fixed
stretch (lts), stretch2.76-5+deb9u4fixed
buster, buster (lts)2.80-1+deb10u2fixed
buster (security)2.80-1+deb10u1fixed
bullseye2.85-1fixed
bookworm2.89-1fixed
sid, trixie2.90-4fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
dnsmasqsourcejessie2.72-3+deb8u6ELA-389-1
dnsmasqsourcestretch2.76-5+deb9u3DLA-2604-1
dnsmasqsourcebuster2.80-1+deb10u1DSA-4844-1
dnsmasqsource(unstable)2.83-1

Notes

https://www.openwall.com/lists/oss-security/2021/01/19/1
https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=4e96a4be685c9e4445f6ee79ad0b36b9119b502a

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