VDB-352436 · CVE-2019-25600 · Exploit 46702

UltraVNC Viewer 1.2.2.4 VNC Server out-of-bounds write

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.2	$0-$5k	0.00

Summaryinfo

A vulnerability classified as critical was found in UltraVNC Viewer 1.2.2.4. The impacted element is an unknown function. Such manipulation of the argument VNC Server leads to out-of-bounds write. This vulnerability is documented as CVE-2019-25600. The attack can be executed remotely. Additionally, an exploit exists.

Detailsinfo

A vulnerability was found in UltraVNC Viewer 1.2.2.4 and classified as problematic. Affected by this issue is an unknown function. The manipulation of the argument VNC Server with an unknown input leads to a out-of-bounds write vulnerability. Using CWE to declare the problem leads to CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. Impacted is availability. CVE summarizes:

UltraVNC Viewer 1.2.2.4 contains a denial of service vulnerability that allows attackers to crash the application by supplying an oversized string to the VNC Server input field. Attackers can paste a malicious string containing 256 repeated characters into the VNC Server field and click Connect to trigger a buffer overflow that crashes the viewer.

The weakness was released by Victor Mondragón as 46702. The advisory is shared for download at exploit-db.com. This vulnerability is handled as CVE-2019-25600 since 03/22/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. Technical details as well as a public exploit are known.

The exploit is available at exploit-db.com. It is declared as proof-of-concept.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Exploit-DB (46702). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Connectivity Software

Vendor

UltraVNC

Name

Viewer

Version

1.2.2.4

License

open-source

CPE 2.3info

🔒

CPE 2.2info

🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.2

VulDB Base Score: 4.3
VulDB Temp Score: 3.9
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.5
CNA Vector (VulnCheck): 🔒

CVSSv2info

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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds write
CWE: CWE-787 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Access: Public
Status: Proof-of-Concept
Download: 🔒

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
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Exploit-DB: 🔒

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

03/22/2026 Advisory disclosed
03/22/2026 +0 days CVE reserved
03/22/2026 +0 days VulDB entry created
03/22/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: 46702
Researcher: Victor Mondragón
Status: Not defined

CVE: CVE-2019-25600 (🔒)
GCVE (CVE): GCVE-0-2019-25600
GCVE (VulDB): GCVE-100-352436
scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 03/22/2026 15:50
Changes: 03/22/2026 15:50 (81)
Complete: 🔍
Cache ID: 216::103