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 a local attacker to cause a denial of service or create
02 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
03 Exploitation and scoring
- Exploitation
- Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
- SSVC decision
- Not assessed by CISA
- EPSS probability
- 0.39% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 33.3% of scored records. A rank, not a probability.
- NVD base score
- 7.8 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- NVD analysis status
- Modified. NVD last modified this record on 2026-06-17.
- Red Hat severity
- No Red Hat rating. Red Hat rates the CVEs that affect its products.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2021-02-17 21:19Z5 YR AGO
- Last updated
- 2024-08-03 20:33Z2 YR AGO
- Reserved
- 2021-02-05
- Assigning CNA
- mitre
- Record state
- PUBLISHED
- Severity
- Not rated by the issuing CNA
- CNA CVSS vector
- Not published by the issuing CNA
- Weaknesses
- CWE-59Improper Link Resolution Before File Access ('Link Following')Base
- Data version
- 5.1
- Document digest
- 065d2b5976a1aa6b226acb7541e044ab476a39e61a352ef9d97961d008db01c9
05 Affected products
06 References
- packages.debian.orghttps://packages.debian.org/buster/avahi-daemon
- packages.debian.orghttps://packages.debian.org/sid/avahi-daemon
- packages.debian.orghttps://packages.debian.org/bullseye/avahi-daemon
- security-tracker.debian.orghttps://security-tracker.debian.org/tracker/CVE-2021-26720
- bugs.launchpad.nethttps://bugs.launchpad.net/ubuntu/+source/avahi/+bug/1870824
- metadata.ftp-master.debian.orghttps://metadata.ftp-master.debian.org/changelogs/main/a/avahi/avahi_0.8-4_changelog
- www.openwall.comhttps://www.openwall.com/lists/oss-security/2021/02/15/2
- bugs.debian.orghttps://bugs.debian.org/cgi-bin/bugreport.cgi?bug=982796
- bugzilla.suse.comhttps://bugzilla.suse.com/show_bug.cgi?id=1180827
- lists.debian.org[debian-lts-announce] 20220607 [SECURITY] [DLA 3047-1] avahi security updatehttps://lists.debian.org/debian-lts-announce/2022/06/msg00009.html
07 Fixed in
Debian 12
- avahi Fixed in 0.8-4
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- avahi Fixed in 0.8-4
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- avahi Fixed in 0.8-4
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 14.04 LTS
- avahi No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 16.04 LTS
- avahi No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 18.04 LTS
- avahi No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.