CVE-2021-26720

NameCVE-2021-26720
Descriptionavahi-daemon-check-dns.sh in the Debian avahi package through 0.8-4 is executed as root via /etc/network/if-up.d/avahi-daemon, and allows a local attacker to cause a denial of service or create arbitrary empty files via a symlink attack on files under /run/avahi-daemon. NOTE: this only affects the packaging for Debian GNU/Linux (used indirectly by SUSE), not the upstream Avahi product.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
avahi (PTS)stretch0.6.32-2vulnerable
buster0.7-4+deb10u1fixed
bullseye, sid0.8-5fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
avahisourcebuster0.7-4+deb10u1
avahisource(unstable)0.8-4

Notes

[stretch] - avahi <postponed> (fix in next DLA - removal of .sh script)
https://www.openwall.com/lists/oss-security/2021/02/15/2
Fixed by removing the avahi-daemon-check-dns.sh script.

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