CVE-2020-27780

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.

Published: 2020-12-18 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-27780 is rated Moderate Risk (59.1/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 0.44%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-27780

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-03-30 1.55% 0.44% -1.12%
2 2025-03-29 0.44% 1.55% +1.12%
3 2025-03-17 — 0.44% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-27780

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
10.0 2.0 HIGH
AV:N/AC:L/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 10.0 10.0 [email protected]

Weakness enumeration for CVE-2020-27780

OS Trackers for CVE-2020-27780

vendor priority summary link
alpine critical CVE-2020-27780: 1 source package rows (linux-pam); 8 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 8, open 0. https://security.alpinelinux.org/vuln/CVE-2020-27780
debian unimportant CVE-2020-27780 unimportant priority: Debian including 1 source packages (pam), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-27780
gentoo normal CVE-2020-27780: 1 GLSA(s) (202012-06), 1 atom(s) (sys-libs/pam); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2020-27780
redhat medium — https://access.redhat.com/security/cve/CVE-2020-27780
suse critical CVE-2020-27780 severity critical: SUSE including 23 source package names (pam, pam-1.5.2-1.1, …), 137 product×package rows across 39 product lines (HPE Helion OpenStack 8, SUSE Enterprise Storage 5, … (39 product lines)): Known Not Affected 121, Fixed 16. https://www.suse.com/security/cve/CVE-2020-27780/
ubuntu high CVE-2020-27780 high priority: Ubuntu including 1 source packages (pam), 6 status rows across 6 suites (bionic, focal, groovy, trusty, upstream, xenial): not-affected 6. https://ubuntu.com/security/CVE-2020-27780

Affected software / configurations for CVE-2020-27780

Vendor Product Version Raw CPE
linux-pam linux-pam >= 1.5.0, < 1.5.1 cpe:2.3:a:linux-pam:linux-pam:*:*:*:*:*:*:*:*

References for CVE-2020-27780

URL Tags
https://bugzilla.redhat.com/show_bug.cgi?id=1901094 Issue Tracking Third Party Advisory
cvelogic Threat Intelligence