CVE-2021-20251

Ubuntu Security Notice USN-5822-2

Severity Score

5.9

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Track

*SSVC

Descriptions

A flaw was found in samba. A race condition in the password lockout code may lead to the risk of brute force attacks being successful if special conditions are met.

Se ha encontrado un fallo en samba. Una condición de ejecución en el código de bloqueo de contraseñas puede conllevar el riesgo de que los ataques de fuerza bruta tengan éxito si se cumplen unas condiciones especiales.

USN-5822-1 fixed vulnerabilities in Samba. The update for Ubuntu 20.04 LTS introduced regressions in certain environments. Pending investigation of these regressions, this update temporarily reverts the security fixes. It was discovered that Samba incorrectly handled the bad password count logic. It was discovered that Samba supported weak RC4/HMAC-MD5 in NetLogon Secure Channel. Greg Hudson discovered that Samba incorrectly handled PAC parsing. Joseph Sutton discovered that Samba could be forced to issue rc4-hmac encrypted Kerberos tickets.

*Credits: N/A

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Attack Vector

Network

Attack Complexity

High

Authentication

None

Confidentiality

None

Integrity

Complete

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:Track

Exploitation

None

Automatable

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2020-12-17 CVE Reserved
2023-01-24 CVE Published
2025-03-06 CVE Updated
2025-03-06 First Exploit
2025-03-30 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CAPEC

References (4)

URL	Tag	Source
https://bugzilla.redhat.com/show_bug.cgi?id=1929800	Issue Tracking
https://security.netapp.com/advisory/ntap-20230331-0005	Third Party Advisory

URL	Date	SRC
https://bugzilla.samba.org/show_bug.cgi?id=14611	2025-03-06

URL	Date	SRC

URL	Date	SRC
https://security.gentoo.org/glsa/202309-06	2023-09-17

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Samba Search vendor "Samba"		Samba Search vendor "Samba" for product "Samba"				>= 4.1.0 < 4.16.8 Search vendor "Samba" for product "Samba" and version " >= 4.1.0 < 4.16.8"		-		Affected
Samba Search vendor "Samba"		Samba Search vendor "Samba" for product "Samba"				>= 4.17.0 < 4.17.4 Search vendor "Samba" for product "Samba" and version " >= 4.17.0 < 4.17.4"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				37 Search vendor "Fedoraproject" for product "Fedora" and version "37"		-		Affected