Link Following The advisory has been revoked - it doesn't affect any version of package avahi (opens in a new tab)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-UBUNTU1604-AVAHI-1076780
- published19 Feb 2021
- disclosed17 Feb 2021
Introduced: 17 Feb 2021
CVE-2021-26720 (opens in a new tab)Amendment
The Ubuntu security team deemed this advisory irrelevant for Ubuntu:16.04.
NVD Description
Note: Versions mentioned in the description apply only to the upstream avahi package and not the avahi package as distributed by Ubuntu.
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.
References
- http://people.ubuntu.com/~ubuntu-security/cve/CVE-2021-26720
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=982796
- https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/1870824
- https://bugzilla.suse.com/show_bug.cgi?id=1180827
- https://metadata.ftp-master.debian.org/changelogs/main/a/avahi/avahi_0.8-4_changelog
- https://packages.debian.org/bullseye/avahi-daemon
- https://packages.debian.org/buster/avahi-daemon
- https://packages.debian.org/sid/avahi-daemon
- https://security-tracker.debian.org/tracker/CVE-2021-26720
- https://www.openwall.com/lists/oss-security/2021/02/15/2
- https://lists.debian.org/debian-lts-announce/2022/06/msg00009.html