CVE-2021-26720

HIGH
Published Feb 17, 20215y ago · Modified Jun 17, 20262w ago
7.8 CVSS 3.1
High
Find Similar
Published Feb 17, 2021 5y ago
Last Modified Jun 17, 2026 2w ago

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 Details

Base Score
7.8
Exploitability
1.8
Impact
5.9
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

No active exploitation signals — not in CISA KEV and no EPSS score yet.

Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-59

Affected Products 3

VendorProductVersionRange
avahiavahi* ≤0.8-4
debiandebian_linux9.0any
debiandebian_linux10.0any

References 10

  • bugs.debian.org https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=982796
    Mailing ListThird Party Advisory
  • bugs.launchpad.net https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/1870824
    Issue TrackingThird Party Advisory
  • bugzilla.suse.com https://bugzilla.suse.com/show_bug.cgi?id=1180827
    Issue TrackingThird Party Advisory
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2022/06/msg00009.html
    Mailing ListThird Party Advisory
  • metadata.ftp-master.debian.org https://metadata.ftp-master.debian.org/changelogs/main/a/avahi/avahi_0.8-4_changelog
    Broken LinkThird Party Advisory
  • packages.debian.org https://packages.debian.org/bullseye/avahi-daemon
    ProductThird Party Advisory
  • packages.debian.org https://packages.debian.org/buster/avahi-daemon
    ProductThird Party Advisory
  • packages.debian.org https://packages.debian.org/sid/avahi-daemon
    ProductThird Party Advisory
  • security-tracker.debian.org https://security-tracker.debian.org/tracker/CVE-2021-26720
    Third Party Advisory
  • openwall.com https://www.openwall.com/lists/oss-security/2021/02/15/2
    Mailing ListThird Party Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.