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Fencer Vulns
critical 9.8

CVE-2020-27780 json

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.

published 2020-12-17 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-20284

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.0%
EPSS 2.0% chance of exploitation in 30 days, percentile 80%
public exploits
0
none known

Summary

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.

Patch / fix

  • linux-pam linux-pam 1.5.1
  • pam openSUSE Tumbleweed 1.5.2-1.1

opensuse advisories openSUSE-SU-2024:11140-1

  • linux-pam Alpine 3.13 1.5.1
  • linux-pam Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 1.5.1-r0

alpine advisories ALPINE-CVE-2020-27780

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • pam Arch Linux 1.5.0-2

arch linux advisories AVG-1297

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-27780 updated cvss 8.1

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

  • Red Hat Enterprise Linux 5 pam Red Hat Enterprise Linux 6 pam Red Hat Enterprise Linux 7 pam Red Hat Enterprise Linux 8 pam
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.96% chance of exploitation in the next 30 days, higher than 80% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • n/a pam

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.