CVE-2019-18276
Published: 28 November 2019
An issue was discovered in disable_priv_mode in shell.c in GNU Bash through 5.0 patch 11. By default, if Bash is run with its effective UID not equal to its real UID, it will drop privileges by setting its effective UID to its real UID. However, it does so incorrectly. On Linux and other systems that support "saved UID" functionality, the saved UID is not dropped. An attacker with command execution in the shell can use "enable -f" for runtime loading of a new builtin, which can be a shared object that calls setuid() and therefore regains privileges. However, binaries running with an effective UID of 0 are unaffected.
Notes
Author | Note |
---|---|
sbeattie | This issue appears to only affect bash when bash is setuid. Ubuntu does not ship with bash setuid, so this has minimal impact for Ubuntu users. This is why we have rated the priority for this issue 'low'. reproducer steps in the suse bugzilla |
Priority
Status
Package | Release | Status |
---|---|---|
bash Launchpad, Ubuntu, Debian |
impish |
Not vulnerable
(5.1-1ubuntu1)
|
bionic |
Released
(4.4.18-2ubuntu1.3)
|
|
disco |
Ignored
(end of life)
|
|
eoan |
Ignored
(end of life)
|
|
focal |
Released
(5.0-6ubuntu1.2)
|
|
groovy |
Ignored
(end of life)
|
|
hirsute |
Not vulnerable
(5.1-1ubuntu1)
|
|
jammy |
Not vulnerable
(5.1-1ubuntu1)
|
|
trusty |
Released
(4.3-7ubuntu1.8+esm2)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only) |
|
upstream |
Released
(5.1)
|
|
xenial |
Released
(4.3-14ubuntu1.4+esm1)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only) |
|
Patches: upstream: https://git.savannah.gnu.org/cgit/bash.git/commit/?h=devel&id=951bdaad7a18cc0dc1036bba86b18b90874d39ff |
Severity score breakdown
Parameter | Value |
---|---|
Base score | 7.8 |
Attack vector | Local |
Attack complexity | Low |
Privileges required | Low |
User interaction | None |
Scope | Unchanged |
Confidentiality | High |
Integrity impact | High |
Availability impact | High |
Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |