CVE-2023-53879VulnerabilityPublished 15 Dec 2025

CVE-2023-53879: neonguvenlik NVClient · Stack-based Buffer Overflow

Affects neonguvenlik NVClientSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

5.3Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Attack Vector: Local
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: Active
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: High
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Local: The vulnerable system 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 through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: Active: Successful exploitation of this vulnerability requires a targeted user to perform specific, conscious interactions with the vulnerable system and the attacker’s payload, or the user’s interactions would actively subvert protection mechanisms which would lead to exploitation of the vulnerability.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: High: There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 15 Dec 2025
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 2026-10-25.

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

Affected software

Product	Affected	Fixed in
neonguvenlik NVClient	Affected =5.0	Fixed in–

AI-suggested

To mitigate CVE-2023-53879, organizations should implement strict input validation and sanitization on the user configuration contact field to prevent buffer overflow conditions. Limiting the maximum length of input accepted in the contact box is critical. Employing application-level controls to detect and block unusually large or malformed inputs can reduce risk. Monitoring NVClient application logs for crashes or abnormal behavior can help identify exploitation attempts early. Where possible, restrict local access to NVClient installations to trusted users only and educate users about the risks of pasting untrusted content into input fields. Until an official patch is released, consider deploying application whitelisting or sandboxing NVClient to contain potential crashes. Engage with neonguvenlik for updates and apply patches promptly once available. Additionally, conduct regular security assessments of client applications to identify similar input validation weaknesses.

Description

CVE-2023-53879 is a medium-severity stack-based buffer overflow vulnerability in neonguvenlik's NVClient version 5.0. The flaw exists in the user configuration contact field, where an attacker can paste a crafted payload to overwrite up to 846 bytes of stack memory, causing the application to crash and resulting in a denial of service (DoS). Exploitation requires local access with low complexity and no privileges, but user interaction is necessary. There are no known exploits in the wild, and no patches have been published yet. The vulnerability impacts availability but does not affect confidentiality or integrity. European organizations using NVClient 5.0, especially in sectors relying on this software for critical operations, may experience service disruptions. Mitigation involves restricting user input length, applying input validation, and monitoring for abnormal application crashes. Countries with higher adoption of neonguvenlik products or strategic sectors using NVClient are more likely to be affected.

Impact

For European organizations using NVClient 5.0, this vulnerability primarily impacts availability by causing application crashes and denial of service. Organizations relying on NVClient for critical communications or operational workflows may face interruptions, potentially affecting productivity and service delivery. Although the vulnerability does not compromise confidentiality or integrity, repeated crashes could lead to operational instability. Sectors such as finance, healthcare, or government agencies using NVClient might experience increased risk due to the potential disruption. Since exploitation requires local access and user interaction, the threat is more significant in environments with shared or less controlled user access, such as open office environments or remote workstations. The absence of known exploits reduces immediate risk but does not eliminate the possibility of future attacks. European entities should be aware of this vulnerability to prevent service degradation and maintain operational continuity.

Summary

CVE-2023-53879 identifies a stack-based buffer overflow vulnerability in neonguvenlik's NVClient version 5.0, specifically within the user configuration contact field. This vulnerability arises because the application fails to properly validate or limit the size of input pasted into the contact box, allowing an attacker to overwrite 846 bytes of stack memory. This memory corruption leads to a denial of service by crashing the application. The vulnerability requires the attacker to have local access to the system and to perform user interaction by pasting a crafted payload into the contact field. No privileges or authentication are required, making it relatively easy to exploit in environments where users have access to the client. The CVSS 4.0 score is 5.3 (medium severity), reflecting the limited impact scope (availability only), low attack complexity, and no requirement for privileges but the need for user interaction. There are no known exploits in the wild, and no patches have been released at the time of publication. The vulnerability does not appear to allow code execution or privilege escalation, but the denial of service could disrupt operations relying on NVClient. The lack of input validation and buffer size checks is the root cause, indicating a need for secure coding practices in handling user input fields.

References

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