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CVE-2023-4255

W3m: out-of-bounds write in function checktype() in etc.c (incomplete fix for cve-2022-38223)

5.5 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.32%Up 0.3 points since Dec 22, 2023
90%50%10%1%

What each source reports

CVE List Score used 5.5

W3m: out-of-bounds write in function checktype() in etc.c (incomplete fix for cve-2022-38223)

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.

Record
CVE-2023-4255
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-787
Updated
2026-11-02
EUVDEUVD-2023-54126 5.5

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.

Record
EUVD-2023-54126
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-03
GitHub AdvisoriesGHSA-hx3r-ph4g-9px9 5.5

An out-of-bounds write issue has been discovered in the backspace handling of the checkType()...

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.

Record
GHSA-hx3r-ph4g-9px9
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-787
Updated
2026-11-02
NVD 5.5

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.

Record
CVE-2023-4255
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-787
Updated
2026-11-02
OSV 5.5

W3m: out-of-bounds write in function checktype() in etc.c (incomplete fix for cve-2022-38223)

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.

Record
CVE-2023-4255
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness
CWE-787
Updated
2026-11-02
OSVDEBIAN-CVE-2023-4255 5.5

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.

Record
DEBIAN-CVE-2023-4255
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 4 moreShow less
OSVUBUNTU-CVE-2023-4255 5.5

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.

Record
UBUNTU-CVE-2023-4255
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVMGASA-2024-0105 No score

Updated w3m packages fix security vulnerabilities

An out-of-bounds read flaw was found in w3m, in the Strnew_size function in Str.c. This issue may allow an attacker to cause a denial of service through a crafted HTML file. (CVE-2023-38252) An out-of-bounds read flaw was found in w3m, in the growbuf_to_Str function in indep.c. This issue may allow an attacker to cause a denial of service through a crafted HTML file. (CVE-2023-38253) 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. (CVE-2023-4255)

Record
MGASA-2024-0105
Updated
2026-11-02
OSVSUSE-SU-2024:0014-1 No score

Security update for w3m

This update for w3m fixes the following issues:

  • CVE-2023-4255: Fixed out-of-bounds write in function checkType() in etc.c (bsc#1218226).
Record
SUSE-SU-2024:0014-1
Updated
2026-11-02
OSVUSN-6580-1 No score

w3m vulnerability

It was discovered that w3m incorrectly handled certain HTML files. An attacker could possibly use this issue to cause a crash or execute arbitrary code.

Record
USN-6580-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
w3m
Debian:12
 All versions, plus listed versions
0.5.3+git20230121-20.5.3+git20230121-2.10.5.3+git20230121-2.20.5.3+git20230121-2.3
 None known
w3m
Debian:13
 before 0.5.3+git20230121-2.1
0.5.3+git20230121-2.1
w3m
Debian:14
 before 0.5.3+git20230121-2.1
0.5.3+git20230121-2.1
w3m
Mageia:9
From an advisory covering 3 CVEs
 before 0.5.3-13.git20230121.1.mga9
0.5.3-13.git20230121.1.mga9
w3m
SUSE:Linux Enterprise Server 12 SP5
 before 0.5.3.git20161120-161.9.1
0.5.3.git20161120-161.9.1
w3m
SUSE:Linux Enterprise Server for SAP Applications 12 SP5
 before 0.5.3.git20161120-161.9.1
0.5.3.git20161120-161.9.1
w3m
Ubuntu:Pro:14.04:LTS
 before 0.5.3-15ubuntu0.2+esm2, plus listed versions
0.5.3-110.5.3-120.5.3-130.5.3-150.5.3-15ubuntu0.10.5.3-15ubuntu0.20.5.3-15ubuntu0.2+esm1
0.5.3-15ubuntu0.2+esm2
w3m
Ubuntu:16.04:LTS
 All versions, plus listed versions
0.5.3-240.5.3-250.5.3-260.5.3-26build10.5.3-26ubuntu0.10.5.3-26ubuntu0.2
 None known
w3m
Ubuntu:Pro:18.04:LTS
 before 0.5.3-36ubuntu0.1+esm1, plus listed versions
0.5.3-340.5.3-34.10.5.3-350.5.3-360.5.3-36build10.5.3-36ubuntu0.1
0.5.3-36ubuntu0.1+esm1
w3m
Ubuntu:20.04:LTS
 before 0.5.3-37ubuntu0.2, plus listed versions
0.5.3-370.5.3-37ubuntu0.1
0.5.3-37ubuntu0.2
w3m
Ubuntu:22.04:LTS
 before 0.5.3+git20210102-6ubuntu0.2, plus listed versions
0.5.3+git20210102-6build10.5.3+git20210102-6build20.5.3+git20210102-6build30.5.3+git20210102-6ubuntu0.1
0.5.3+git20210102-6ubuntu0.2
w3m
Ubuntu:24.04:LTS
 before 0.5.3+git20230121-2ubuntu1, plus listed versions
0.5.3+git20230121-2
0.5.3+git20230121-2ubuntu1

History

History
RecordedChangedSources
affected, facts
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2023-4255 is a medium vulnerability (CVSS 5.5) in Tats W3m, published December 21, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.32%, the 25th percentile. Fixed in w3m 0.5.3+git20230121-2.1.

References

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