CVE-2021-44730

snapd 2.54.2 did not properly validate the location of the snap-confine binary. A local attacker who can hardlink this binary to another location to cause snap-confine to execute other arbitrary binaries and hence gain privilege escalation. Fixed in snapd versions 2.54.3+18.04, 2.54.3+20.04 and 2.54.3+21.10.1

Weakness

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

Affected Software

Name	Vendor	Start Version	End Version
Snapd	Canonical	*	2.54.2 (including)
Snapd	Ubuntu	bionic	*
Snapd	Ubuntu	devel	*
Snapd	Ubuntu	esm-infra/bionic	*
Snapd	Ubuntu	esm-infra/focal	*
Snapd	Ubuntu	esm-infra/xenial	*
Snapd	Ubuntu	focal	*
Snapd	Ubuntu	hirsute	*
Snapd	Ubuntu	impish	*
Snapd	Ubuntu	snap	*
Snapd	Ubuntu	trusty/esm	*
Snapd	Ubuntu	upstream	*

Potential Mitigations

Follow the principle of least privilege when assigning access rights to entities in a software system.
Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

NVD	https://nvd.nist.gov/vuln/detail/CVE-2021-44730
CWE	https://cwe.mitre.org/data/definitions/59.html

Improper Link Resolution Before File Access ('Link Following')

Weakness

Affected Software

Potential Mitigations

References

CVE-2021-44730

Improper Link Resolution Before File Access ('Link Following')

Weakness

Affected Software

Potential Mitigations

Related Attack Patterns

References