| Name | CVE-2021-26720 |
| Description | avahi-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. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-3047-1, ELA-624-1 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| avahi (PTS) | jessie, jessie (lts) | 0.6.31-5+deb8u3 | fixed |
| stretch (security) | 0.6.32-2+deb9u1 | fixed | |
| stretch (lts), stretch | 0.6.32-2+deb9u3 | fixed | |
| buster, buster (lts) | 0.7-4+deb10u4 | fixed | |
| buster (security) | 0.7-4+deb10u3 | fixed | |
| bullseye | 0.8-5+deb11u2 | fixed | |
| bullseye (security) | 0.8-5+deb11u3 | fixed | |
| bookworm | 0.8-10+deb12u1 | fixed | |
| sid, trixie | 0.8-16 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| avahi | source | jessie | 0.6.31-5+deb8u1 | ELA-624-1 | ||
| avahi | source | stretch | 0.6.32-2+deb9u1 | DLA-3047-1 | ||
| avahi | source | buster | 0.7-4+deb10u1 | |||
| avahi | source | (unstable) | 0.8-4 |
https://www.openwall.com/lists/oss-security/2021/02/15/2
Fixed by removing the avahi-daemon-check-dns.sh script.