CVE-2021-26720

Severity Score

7.8

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

El archivo avahi-daemon-check-dns.sh en el paquete Debian avahi a versiones hasta 0.8-4, es ejecutado como root por medio de /etc/network/if-up.d/avahi-daemon, y permite a un atacante local causar una denegación de servicio o crear archivos vacíos arbitrarios por medio de un ataque de tipo symlink en archivos bajo /run/avahi-daemon. NOTA: esto solo afecta al empaquetado de Debian GNU/Linux (usado indirectamente por SUSE), no al producto de Avahi previo

*Credits: N/A

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Local

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-02-05 CVE Reserved
2021-02-17 CVE Published
2023-03-08 EPSS Updated
2024-08-03 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-59: Improper Link Resolution Before File Access ('Link Following')

CAPEC

References (10)

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

URL	Date	SRC

URL	Date	SRC

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Avahi Search vendor "Avahi"		Avahi Search vendor "Avahi" for product "Avahi"				<= 0.8-4 Search vendor "Avahi" for product "Avahi" and version " <= 0.8-4"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				9.0 Search vendor "Debian" for product "Debian Linux" and version "9.0"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				10.0 Search vendor "Debian" for product "Debian Linux" and version "10.0"		-		Affected