w3m etc.c checkType out-of-bounds write

HistoryDiffrelatejsonxmlCTI

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.
4.8	$0-$5k	0.00

Summaryinfo

A vulnerability categorized as critical has been discovered in w3m. This vulnerability affects the function checkType of the file etc.c. Executing a manipulation can lead to out-of-bounds write. This vulnerability is handled as CVE-2023-4255. The attack can be executed remotely. There is not any exploit available. A patch should be applied to remediate this issue.

Detailsinfo

A vulnerability has been found in w3m (Web Browser) (affected version unknown) and classified as critical. This vulnerability affects the function checkType of the file etc.c. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. The CWE definition for the vulnerability is CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect availability. CVE summarizes:

An out-of-bounds write issue has been discovered in the backspace handling of the checkType() function in etc.c within the W3M application. This vulnerability is triggered by supplying a specially crafted HTML file to the w3m binary. Exploitation of this flaw could lead to application crashes, resulting in a denial of service condition.

The weakness was released 12/21/2023 as 268. The advisory is available at github.com. This vulnerability was named CVE-2023-4255 since 08/08/2023. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 239825 (TencentOS Server 4: w3m (TSSA-2025:0165)), which helps to determine the existence of the flaw in a target environment.

Applying the patch edc602651c506aeeb60544b55534dd1722a340d3 is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the vulnerability database at Tenable (239825). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

Web Browser

Name

License

open-source

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.9
VulDB Meta Temp Score: 4.8

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

CNA Base Score: 5.5
CNA Vector (Red Hat, Inc.): 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

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

Physical: Partially
Local: Yes
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 239825
Nessus Name: TencentOS Server 4: w3m (TSSA-2025:0165)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔍

Patch: edc602651c506aeeb60544b55534dd1722a340d3

Timelineinfo

08/08/2023 🔍
12/21/2023 +135 days 🔍
12/21/2023 +0 days 🔍
06/20/2025 +547 days 🔍

Sourcesinfo

Advisory: 268
Status: Confirmed

CVE: CVE-2023-4255 (🔍)
GCVE (CVE): GCVE-0-2023-4255
GCVE (VulDB): GCVE-100-248746

Entryinfo

Created: 12/21/2023 17:23
Updated: 06/20/2025 04:19
Changes: 12/21/2023 17:23 (52), 06/20/2025 04:19 (21)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.