7.5
CVSSv3

CVE-2019-7303

Published: 23/04/2019 Updated: 16/10/2020
CVSS v2 Base Score: 5 | Impact Score: 2.9 | Exploitability Score: 10
CVSS v3 Base Score: 7.5 | Impact Score: 3.6 | Exploitability Score: 3.9
VMScore: 505
Vector: AV:N/AC:L/Au:N/C:N/I:P/A:N

Vulnerability Summary

A vulnerability in the seccomp filters of Canonical snapd before version 2.37.4 allows a strict mode snap to insert characters into a terminal on a 64-bit host. The seccomp rules were generated to match 64-bit ioctl(2) commands on a 64-bit platform; however, the Linux kernel only uses the lower 32 bits to determine which ioctl(2) commands to run. This issue affects: Canonical snapd versions before 2.37.4.

Vulnerability Trend

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canonical snapd

canonical ubuntu linux 14.04

canonical ubuntu linux 18.04

canonical ubuntu linux 16.04

canonical ubuntu linux 18.10

Vendor Advisories

Debian Bug report logs - #925541 CVE-2019-10063: incomplete TIOCSTI filtering, similar to snapd's CVE-2019-7303 Package: flatpak; Maintainer for flatpak is Utopia Maintenance Team <pkg-utopia-maintainers@listsaliothdebianorg>; Source for flatpak is src:flatpak (PTS, buildd, popcon) Reported by: Simon McVittie <smcv@deb ...
An intended access restriction in snapd could be bypassed by strict mode snaps on 64 bit architectures ...

Exploits

/* snap uses a seccomp filter to prevent the use of the TIOCSTI ioctl; in the source code, this filter is expressed as follows: # TIOCSTI allows for faking input (man tty_ioctl) # TODO: this should be scaled back even more ioctl - !TIOCSTI In the X86-64 version of the compiled seccomp filter, this results in the following BPF bytecode: [ ...
snap uses a seccomp filter with a blacklist for TIOCSTI can be circumvented ...