CVE-2021-4120

snapd 2.54.2 fails to perform sufficient validation of snap content interface and layout paths, resulting in the ability for snaps to inject arbitrary AppArmor policy rules via malformed content interface and layout declarations and hence escape strict snap confinement. Fixed in snapd versions 2.54.3+18.04, 2.54.3+20.04 and 2.54.3+21.10.1

James Troup discovered that snap did not properly manage the permissions for the snap directories. A local attacker could possibly use this issue to expose sensitive information. (CVE-2021-3155)

Ian Johnson discovered that snapd did not properly validate content interfaces and layout paths. A local attacker could possibly use this issue to inject arbitrary AppArmor policy rules, resulting in a bypass of intended access restrictions. (CVE-2021-4120)

The Qualys Research Team discovered that snapd did not properly validate the location of the snap-confine binary. A local attacker could possibly use this issue to execute other arbitrary binaries and escalate privileges. (CVE-2021-44730)

The Qualys Research Team discovered that a race condition existed in the snapd snap-confine binary when preparing a private mount namespace for a snap. A local attacker could possibly use this issue to escalate privileges and execute arbitrary code. (CVE-2021-44731)

USN-5292-1 fixed vulnerabilities in snapd. This update provides the corresponding update for the riscv64 architecture.

Original advisory details:

James Troup discovered that snap did not properly manage the permissions for the snap directories. A local attacker could possibly use this issue to expose sensitive information. (CVE-2021-3155)

Ian Johnson discovered that snapd did not properly validate content interfaces and layout paths. A local attacker could possibly use this issue to inject arbitrary AppArmor policy rules, resulting in a bypass of intended access restrictions. (CVE-2021-4120)

The Qualys Research Team discovered that snapd did not properly validate the location of the snap-confine binary. A local attacker could possibly use this issue to execute other arbitrary binaries and escalate privileges. (CVE-2021-44730)

The Qualys Research Team discovered that a race condition existed in the snapd snap-confine binary when preparing a private mount namespace for a snap. A local attacker could possibly use this issue to escalate privileges and execute arbitrary code. (CVE-2021-44731)

USN-5292-1 fixed several vulnerabilities in snapd. This update provides the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.

Original advisory details:

James Troup discovered that snap did not properly manage the permissions for the snap directories. A local attacker could possibly use this issue to expose sensitive information. (CVE-2021-3155)

Ian Johnson discovered that snapd did not properly validate content interfaces and layout paths. A local attacker could possibly use this issue to inject arbitrary AppArmor policy rules, resulting in a bypass of intended access restrictions. (CVE-2021-4120)

The Qualys Research Team discovered that snapd did not properly validate the location of the snap-confine binary. A local attacker could possibly use this issue to execute other arbitrary binaries and escalate privileges. (CVE-2021-44730)

The Qualys Research Team discovered that a race condition existed in the snapd snap-confine binary when preparing a private mount namespace for a snap. A local attacker could possibly use this issue to escalate privileges and execute arbitrary code. (CVE-2021-44731)