PT-2021-7394 · Debian+2 · Avahi+2

Matthias Gerstner · Published 2021-02-15 · Updated 2024-07-23 · CVE-2021-26720

Positive Technologies (AI Summary)

CVSS v3.1

7.8

High

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions avahi-daemon-check-dns.sh in the Debian avahi package through 0.8-4

Description The issue is related to the execution of avahi-daemon-check-dns.sh as root via /etc/network/if-up.d/avahi-daemon, allowing a local attacker to cause a denial of service or create arbitrary empty files via a symlink attack on files under /run/avahi-daemon. This affects the packaging for Debian GNU/Linux, used indirectly by SUSE, but not the upstream Avahi product. The vulnerability can also lead to unauthorized access to confidential data and disruption of their integrity.

Recommendations For avahi-daemon-check-dns.sh in the Debian avahi package through 0.8-4, consider disabling the execution of the script as root via /etc/network/if-up.d/avahi-daemon as a temporary workaround to minimize the risk of exploitation. Restrict access to files under /run/avahi-daemon to prevent a symlink attack. At the moment, there is no information about a newer version that contains a fix for this vulnerability.

DoS

Link Following

Weakness Enumeration

CWE-59

Related Identifiers

AZL-34547

AZL-6323

BDU:2022-05969

CVE-2021-26720

DLA-3047-1

OPENSUSE-SU-2021:0370-1

OPENSUSE-SU-2021:1845-1

OPENSUSE-SU-2021_0370-1

OPENSUSE-SU-2021_1845-1

OPENSUSE-SU-2024:10643-1

ROSA-SA-2024-2455

SUSE-SU-2021:0551-1

SUSE-SU-2021:0563-1

SUSE-SU-2021:1845-1

SUSE-SU-2021_0551-1

SUSE-SU-2021_0563-1

SUSE-SU-2021_1845-1

Affected Products

Astra Linux

Suse

Avahi

References · 47

• https://cve.org/CVERecord?id=CVE-2021-26720 · Security Note
• https://osv.dev/vulnerability/DLA-3047-1 · Vendor Advisory
• https://wiki.astralinux.ru/astra-linux-se81-bulletin-20230315SE81 · Vendor Advisory
• https://osv.dev/vulnerability/openSUSE-SU-2024:10643-1 · Vendor Advisory
• https://osv.dev/vulnerability/ALPINE-CVE-2021-26720 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2021:0563-1 · Vendor Advisory
• https://bdu.fstec.ru/vul/2022-05969 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-26720 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2021-26720 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2021:0551-1 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2021-26720 · Vendor Advisory
• https://osv.dev/vulnerability/AZL-6323 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-26720 · Security Note
• https://osv.dev/vulnerability/openSUSE-SU-2021:0370-1 · Vendor Advisory
• https://osv.dev/vulnerability/openSUSE-SU-2021:1845-1 · Vendor Advisory