CVE-2023-4641VulnerabilityPublished 27 Dec 2023Updated 3 Nov 2025

CVE-2023-4641: Incorrect Implementation of Authentication Algorithm

Source CVE Database V5

Not known to be exploited · CVSS 4.7 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

4.7Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Local
Attack Complexity: High
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 27 Dec 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

AI-suggested

To mitigate CVE-2023-4641, organizations should monitor for and apply security patches from their Linux distribution vendors as soon as they become available. In the interim, restrict local access to trusted users only, minimizing the risk of an attacker gaining the necessary access to exploit this vulnerability. Employ strict user privilege separation and auditing to detect unauthorized access attempts. Consider using memory protection mechanisms and tools that can detect or prevent unauthorized memory reads. Additionally, educate system administrators and users about the risks of password management vulnerabilities and encourage the use of multi-factor authentication to reduce the impact of credential compromise. Regularly review and harden system configurations to limit local access vectors, and implement monitoring solutions to detect suspicious activities related to password changes or memory access.

Description

A flaw was found in shadow-utils. When asking for a new password, shadow-utils asks the password twice. If the password fails on the second attempt, shadow-utils fails in cleaning the buffer used to store the first entry. This may allow an attacker with enough access to retrieve the password from the memory.

Impact

The primary impact of CVE-2023-4641 is on the confidentiality of user passwords during the password change process. An attacker with local access and limited privileges could potentially retrieve the first password attempt from memory if the second password entry fails. This exposure could lead to unauthorized access if the attacker obtains valid credentials. For European organizations, especially those operating multi-user Linux servers or shared environments, this vulnerability increases the risk of credential compromise. Critical sectors such as finance, government, and telecommunications that rely heavily on Linux infrastructure could face increased insider threat risks or lateral movement opportunities for attackers. However, the vulnerability does not affect system integrity or availability, and exploitation requires local access, limiting the scope to insider threats or attackers who have already gained some foothold. The absence of known exploits in the wild reduces immediate risk but does not eliminate the potential for future exploitation.

References

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