CVE-2021-26720
Published: 17 February 2021
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.
Notes
| Author | Note |
|---|---|
| mdeslaur | the script was removed in the 0.7-4ubuntu7 package in focal. for bionic and earlier, we can't simply remove the script as libnss-mdns is too old there. |
| litios | there is no upstream patch available to fix this issue, as the proposed fix was to delete the script file. marking as deferred |
Priority
Status
| Package | Release | Status |
|---|---|---|
|
avahi Launchpad, Ubuntu, Debian |
bionic |
Deferred
|
| focal |
Not vulnerable
(0.7-4ubuntu7)
|
|
| groovy |
Not vulnerable
(0.8-3ubuntu1)
|
|
| hirsute |
Not vulnerable
(0.8-3ubuntu2)
|
|
| impish |
Not vulnerable
(0.8-3ubuntu2)
|
|
| jammy |
Not vulnerable
(0.8-3ubuntu2)
|
|
| kinetic |
Not vulnerable
(0.8-3ubuntu2)
|
|
| lunar |
Not vulnerable
(0.8-3ubuntu2)
|
|
| mantic |
Not vulnerable
(0.8-3ubuntu2)
|
|
| trusty |
Deferred
|
|
| upstream |
Not vulnerable
(code not present)
|
|
| xenial |
Deferred
|
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7.8 |
| Attack vector | Local |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity impact | High |
| Availability impact | High |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |