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cve[email protected]CVE-2021-43860
HistoryJan 12, 2022 - 10:15 p.m.

CVE-2021-43860

2022-01-1222:15:00
CWE-276
web.nvd.nist.gov
132
cve-2021-43860
flatpak
linux
application sandboxing
distribution framework
permissions
security vulnerability
update
nvd

8.6 High

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

8.2 High

AI Score

Confidence

High

6.8 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:P/I:P/A:P

0.002 Low

EPSS

Percentile

53.9%

Flatpak is a Linux application sandboxing and distribution framework. Prior to versions 1.12.3 and 1.10.6, Flatpak doesn’t properly validate that the permissions displayed to the user for an app at install time match the actual permissions granted to the app at runtime, in the case that there’s a null byte in the metadata file of an app. Therefore apps can grant themselves permissions without the consent of the user. Flatpak shows permissions to the user during install by reading them from the “xa.metadata” key in the commit metadata. This cannot contain a null terminator, because it is an untrusted GVariant. Flatpak compares these permissions to the actual metadata, from the “metadata” file to ensure it wasn’t lied to. However, the actual metadata contents are loaded in several places where they are read as simple C-style strings. That means that, if the metadata file includes a null terminator, only the content of the file from before the terminator gets compared to xa.metadata. Thus, any permissions that appear in the metadata file after a null terminator are applied at runtime but not shown to the user. So maliciously crafted apps can give themselves hidden permissions. Users who have Flatpaks installed from untrusted sources are at risk in case the Flatpak has a maliciously crafted metadata file, either initially or in an update. This issue is patched in versions 1.12.3 and 1.10.6. As a workaround, users can manually check the permissions of installed apps by checking the metadata file or the xa.metadata key on the commit metadata.

VendorProductVersionCPE
flatpakflatpak*cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:*
flatpakflatpak*cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:*

8.6 High

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

8.2 High

AI Score

Confidence

High

6.8 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:P/I:P/A:P

0.002 Low

EPSS

Percentile

53.9%