Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Avahi | Avahi | <= 0.8-4 |
| Debian | Debian Linux | 9.0 |
Related Weaknesses (CWE)
References
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=982796Mailing ListThird Party Advisory
- https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/1870824Issue TrackingThird Party Advisory
- https://bugzilla.suse.com/show_bug.cgi?id=1180827Issue TrackingThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/06/msg00009.htmlMailing ListThird Party Advisory
- https://metadata.ftp-master.debian.org/changelogs/main/a/avahi/avahi_0.8-4_changBroken LinkThird Party Advisory
- https://packages.debian.org/bullseye/avahi-daemonProductThird Party Advisory
- https://packages.debian.org/buster/avahi-daemonProductThird Party Advisory
- https://packages.debian.org/sid/avahi-daemonProductThird Party Advisory
- https://security-tracker.debian.org/tracker/CVE-2021-26720Third Party Advisory
- https://www.openwall.com/lists/oss-security/2021/02/15/2Mailing ListThird Party Advisory
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=982796Mailing ListThird Party Advisory
- https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/1870824Issue TrackingThird Party Advisory
- https://bugzilla.suse.com/show_bug.cgi?id=1180827Issue TrackingThird Party Advisory
- https://lists.debian.org/debian-lts-announce/2022/06/msg00009.htmlMailing ListThird Party Advisory
- https://metadata.ftp-master.debian.org/changelogs/main/a/avahi/avahi_0.8-4_changBroken LinkThird Party Advisory
FAQ
What is CVE-2021-26720?
CVE-2021-26720 is a vulnerability with a CVSS score of 7.8 (HIGH). 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 arbitr...
How severe is CVE-2021-26720?
CVE-2021-26720 has been rated HIGH with a CVSS base score of 7.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2021-26720?
Check the references section above for vendor advisories and patch information. Affected products include: Avahi Avahi, Debian Debian Linux.