CVE-2019-18634

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 19.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2020-01-29 · updated 2026-06-17
Weakness: CWE-787

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.

Affected products

Debian Linux: 8.0, 9.0, 10.0
sudo: from 1.7.1 before 1.8.26 — fixed in 1.8.26

How to fix

Upgrade to a fixed version: sudo 1.8.26. Check the vendor advisory for mitigations.

References

http://lists.opensuse.org/opensuse-security-announce/2020-02/msg00029.html
http://packetstormsecurity.com/files/156174/Slackware-Security-Advisory-sudo-Updates.html
http://packetstormsecurity.com/files/156189/Sudo-1.8.25p-Buffer-Overflow.html
http://seclists.org/fulldisclosure/2020/Jan/40
http://www.openwall.com/lists/oss-security/2020/01/30/6
http://www.openwall.com/lists/oss-security/2020/01/31/1
http://www.openwall.com/lists/oss-security/2020/02/05/2
http://www.openwall.com/lists/oss-security/2020/02/05/5
https://access.redhat.com/errata/RHSA-2020:0487
https://access.redhat.com/errata/RHSA-2020:0509
https://access.redhat.com/errata/RHSA-2020:0540
https://access.redhat.com/errata/RHSA-2020:0726

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