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Vulnerabilities / CVE-2020-27780

critical

CVE-2020-27780

pam: authentication bypass when the user doesn't exist and root password is blank

Published Modified CWE 287
In the Trivy database since at least 24 Oct 2026, 07:11 UTCWhen it arrived before that build is not recorded.

Severity by source

NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat8.1CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Trivy's own label is CRITICAL. Rated critical by NVD, CBL-Mariner. Rated lower by Red Hat (medium).

Description

A flaw was found in Linux-Pam in versions prior to 1.5.1 in the way it handle empty passwords for non-existing users. When the user doesn't exist PAM try to authenticate with root and in the case of an empty password it successfully authenticate.

Affected packages and fixed versions

SourcePackageFixed in
CBL-Mariner 1.0pam0:1.5.1-2.cm1
alpine 3.13linux-pam1.5.1
alpine 3.14linux-pam1.5.1-r0
alpine 3.15linux-pam1.5.1-r0
alpine 3.16linux-pam1.5.1-r0
alpine 3.17linux-pam1.5.1-r0
alpine 3.18linux-pam1.5.1-r0
alpine 3.19linux-pam1.5.1-r0
alpine 3.20linux-pam1.5.1-r0
alpine 3.21linux-pam1.5.1-r0
alpine 3.22linux-pam1.5.1-r0
alpine 3.23linux-pam1.5.1-r0
Show all 16 entries from 16 sources
SourcePackageFixed in
CBL-Mariner 1.0pam0:1.5.1-2.cm1
alpine 3.13linux-pam1.5.1
alpine 3.14linux-pam1.5.1-r0
alpine 3.15linux-pam1.5.1-r0
alpine 3.16linux-pam1.5.1-r0
alpine 3.17linux-pam1.5.1-r0
alpine 3.18linux-pam1.5.1-r0
alpine 3.19linux-pam1.5.1-r0
alpine 3.20linux-pam1.5.1-r0
alpine 3.21linux-pam1.5.1-r0
alpine 3.22linux-pam1.5.1-r0
alpine 3.23linux-pam1.5.1-r0
alpine 3.24linux-pam1.5.1-r0
alpine edgelinux-pam1.5.1-r0
root.io alpine 3.18rootio-linux-pam1.5.1-r0
root.io alpine 3.19rootio-linux-pam1.5.1-r0

References

Vulnerability data compiled from the Trivy vulnerability database (trivy-db, Aqua Security, Apache License 2.0), which aggregates third-party advisories. CVE records are published by The MITRE Corporation under the CVE Terms of Use; CVE is a trademark of MITRE. This product uses data from the NVD API but is not endorsed or certified by the NVD. Severity, titles and advisory data from the GitHub Advisory Database (CC BY 4.0), Red Hat security data (CC BY 4.0) and the other sources linked on each entry. Entries may be summarised or re-formatted; the linked original is the authoritative record.