UBUNTU-CVE-2021-26720

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Source
https://ubuntu.com/security/CVE-2021-26720
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-26720.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2021-26720
Upstream
Published
2021-02-17T22:15:00Z
Modified
2025-07-16T08:15:34.864623Z
Severity
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
  • Ubuntu - low
Summary
[none]
Details

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

Affected packages

Ubuntu:Pro:14.04:LTS / avahi

Package

Name
avahi
Purl
pkg:deb/ubuntu/avahi@0.6.31-4ubuntu1.3+esm3?arch=source&distro=esm-infra-legacy/trusty

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*

0.6.31-2ubuntu4
0.6.31-2ubuntu5
0.6.31-3ubuntu1
0.6.31-4ubuntu1
0.6.31-4ubuntu1.1
0.6.31-4ubuntu1.2
0.6.31-4ubuntu1.3
0.6.31-4ubuntu1.3+esm1
0.6.31-4ubuntu1.3+esm2
0.6.31-4ubuntu1.3+esm3

Ubuntu:Pro:16.04:LTS / avahi

Package

Name
avahi
Purl
pkg:deb/ubuntu/avahi@0.6.32~rc+dfsg-1ubuntu2.3+esm3?arch=source&distro=esm-infra/xenial

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*

0.6.31-4ubuntu4
0.6.32~rc+dfsg-1ubuntu2
0.6.32~rc+dfsg-1ubuntu2.1
0.6.32~rc+dfsg-1ubuntu2.2
0.6.32~rc+dfsg-1ubuntu2.3
0.6.32~rc+dfsg-1ubuntu2.3+esm1
0.6.32~rc+dfsg-1ubuntu2.3+esm2
0.6.32~rc+dfsg-1ubuntu2.3+esm3

Ubuntu:Pro:18.04:LTS / avahi

Package

Name
avahi
Purl
pkg:deb/ubuntu/avahi@0.7-3.1ubuntu1.3+esm2?arch=source&distro=esm-infra/bionic

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*

0.6.32-1ubuntu1
0.7-3ubuntu1
0.7-3ubuntu2
0.7-3.1ubuntu1
0.7-3.1ubuntu1.1
0.7-3.1ubuntu1.2
0.7-3.1ubuntu1.3
0.7-3.1ubuntu1.3+esm1
0.7-3.1ubuntu1.3+esm2

Ubuntu:20.04:LTS / avahi

Package

Name
avahi
Purl
pkg:deb/ubuntu/avahi@0.7-4ubuntu7?arch=source&distro=focal

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
0.7-4ubuntu7

Affected versions

0.*

0.7-4ubuntu5
0.7-4ubuntu6

Ecosystem specific 

{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_name": "avahi-autoipd",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "avahi-autoipd-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "avahi-daemon",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "avahi-daemon-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "avahi-discover",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "avahi-dnsconfd",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "avahi-dnsconfd-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "avahi-ui-utils",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "avahi-ui-utils-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "avahi-utils",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "avahi-utils-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "gir1.2-avahi-0.6",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-client-dev",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-client3",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-client3-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-common-data",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-common-dev",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-common3",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-common3-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-common3-udeb",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-compat-libdnssd-dev",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-compat-libdnssd1",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-compat-libdnssd1-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-core-dev",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-core7",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-core7-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-core7-udeb",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-glib-dev",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-glib1",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-glib1-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-gobject-dev",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-gobject0",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-gobject0-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-ui-gtk3-0",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-ui-gtk3-0-dbgsym",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "libavahi-ui-gtk3-dev",
            "binary_version": "0.7-4ubuntu7"
        },
        {
            "binary_name": "python-avahi",
            "binary_version": "0.7-4ubuntu7"
        }
    ]
}