Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2020-27780

29
FAUCET Score

CVE-2020-27780 describes a critical authentication bypass vulnerability in Linux-PAM versions prior to 1.5.1. This flaw allows an unauthenticated attacker to gain root access by attempting to log in as a non-existent user with an empty password. The vulnerability carries a CVSS score of 9.8 (Critical) due to its network-based attack vector, low complexity, and complete compromise of confidentiality, integrity, and availability. Despite its severity, there is no evidence of active exploitation, publicly available exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
>= 1.5.0, < 1.5.1CPE matchmatch criteria
cpe:2.3:a:linux-pam:linux-pam:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.96%
Probability of exploitation in next 30 days
EPSS Percentile
78.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0196 is in the 67th percentile among its peer group of 36,835 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

microsoftpatch availablevia msrc
Product: 19141-16820Fixed in: 1.5.1-2
microsoftpatch availablevia msrc
Product: cm1 pam 1.5.1-2 on CBL Mariner 1.0Fixed in: 1.5.1-2

Vendor Advisories (2)

microsoft2020-Dec/CVE-2020-27780Critical

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.

Dec 8, 2020
redhatCVE-2020-27780Moderate

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

Oct 27, 2020

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingThird Party Advisory