| Name | CVE-2019-18634 |
| Description | In Sudo before 1.8.26, if pwfeedback is enabled in /etc/sudoers, users can trigger a stack-based buffer overflow in the privileged sudo process. (pwfeedback is a default setting in Linux Mint and elementary OS; however, it is NOT the default for upstream and many other packages, and would exist only if enabled by an administrator.) The attacker needs to deliver a long string to the stdin of getln() in tgetpass.c. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-2094-1, DSA-4614-1, ELA-213-1 |
| Debian Bugs | 950371 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| sudo (PTS) | jessie, jessie (lts) | 1.8.10p3-1+deb8u9 | fixed |
| stretch (security) | 1.8.19p1-2.1+deb9u3 | fixed | |
| stretch (lts), stretch | 1.8.19p1-2.1+deb9u6 | fixed | |
| buster (security), buster, buster (lts) | 1.8.27-1+deb10u6 | fixed | |
| bullseye (security), bullseye | 1.9.5p2-3+deb11u1 | fixed | |
| bookworm | 1.9.13p3-1+deb12u1 | fixed | |
| sid, trixie | 1.9.16p1-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| sudo | source | wheezy | 1.8.5p2-1+nmu3+deb7u6 | ELA-213-1 | ||
| sudo | source | jessie | 1.8.10p3-1+deb8u7 | DLA-2094-1 | ||
| sudo | source | stretch | 1.8.19p1-2.1+deb9u2 | DSA-4614-1 | ||
| sudo | source | buster | 1.8.27-1+deb10u2 | |||
| sudo | source | (unstable) | 1.8.31-1 | 950371 |
https://www.sudo.ws/alerts/pwfeedback.html
https://www.openwall.com/lists/oss-security/2020/01/30/6
https://github.com/sudo-project/sudo/commit/fa8ffeb17523494f0e8bb49a25e53635f4509078 (master)
https://github.com/sudo-project/sudo/commit/b5d2010b6514ff45693509273bb07df3abb0bf0a (SUDO_1_8_31)
The issue itself is fixed only in 1.8.31 but a change in the EOF handling
introduced in 1.8.26 mitigated exploitation of the bug in some cases:
https://www.openwall.com/lists/oss-security/2020/01/31/1
Change for "Print a warning for password read issues" in 1.8.26:
https://github.com/sudo-project/sudo/commit/ab2cba0f5d8b286e8e52c06076efd32434f538ae (SUDO_1_8_26)
The overflow is tough as well reachable when using a pty:
https://www.openwall.com/lists/oss-security/2020/02/05/2