CVE-2021-26720
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…
- Published
- Updated
- Reserved
- Assigned by
- mitre
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.
Timeline
ID reserved
By mitre
- 12 days later
· 12 days later
Published
- 3 years later
· 3 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.40% · top 66% of all CVEs (7 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Weakness
Affected products
n/a
- affected n/a
References (10)
- https://packages.debian.org/buster/avahi-daemon (opens in a new tab)x_refsource_MISCx_transferred
- https://packages.debian.org/sid/avahi-daemon (opens in a new tab)x_refsource_MISCx_transferred
- https://packages.debian.org/bullseye/avahi-daemon (opens in a new tab)x_refsource_MISCx_transferred
- https://security-tracker.debian.org/tracker/CVE-2021-26720 (opens in a new tab)x_refsource_MISCx_transferred
- https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/1870824 (opens in a new tab)x_refsource_MISCx_transferred
- https://metadata.ftp-master.debian.org/changelogs/main/a/avahi/avahi_0.8-4_changelog (opens in a new tab)x_refsource_MISCx_transferred
- https://www.openwall.com/lists/oss-security/2021/02/15/2 (opens in a new tab)x_refsource_MISCx_transferred
- https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=982796 (opens in a new tab)x_refsource_MISCx_transferred
- https://bugzilla.suse.com/show_bug.cgi?id=1180827 (opens in a new tab)x_refsource_MISCx_transferred
- [debian-lts-announce] 20220607 [SECURITY] [DLA 3047-1] avahi security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2021-26720)Record last updated .