Summary
The snapd default seccomp filter for strict mode snaps blocks the use of
the ioctl() system call when used with TIOCSTI as the second argument to
the system call. Jann Horn discovered that this restriction could be
circumvented on 64 bit architectures. A malicious snap could exploit this
to bypass intended access restrictions to insert characters into the
terminal's input queue. On Ubuntu, snapd typically will have already
automatically refreshed itself to snapd 2.37.4 which is unaffected.
Fixed packages 3
| Release | Package | Fixed in |
|---|---|---|
| Ubuntu · 14.04 LTS 14.04:LTS | snapd | 2.37.4~14.04.1 |
| Ubuntu · 16.04 LTS 16.04:LTS | snapd | 2.37.4ubuntu0.1 |
| Ubuntu · 18.04 LTS 18.04:LTS | snapd | 2.37.4+18.04.1 |
Vulnerabilities 1
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Medium 5.7CVE-2019-7303 Public exploit
Snapd seccomp filter TIOCSTI ioctl bypass
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, …