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CVE-2021-40647

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter...

5.5 MediumFix available

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter in the top chunk of the heap. This at least causes the program to segmentation abort if the heap size parameter isn't aligned correctly. In version before GLIBC version 2.29 and aligned correctly, it allows arbitrary write anywhere in the programs memory.

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

0.34%Down 0.5 points since Sep 10, 2022
90%50%10%1%

What each source reports

NVD Score used 5.5

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter in the top chunk of the heap. This at least causes the program to segmentation abort if the heap size parameter isn't aligned correctly. In version before GLIBC version 2.29 and aligned correctly, it allows arbitrary write anywhere in the programs memory.

Record
CVE-2021-40647
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
CVE List No score

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter in the top chunk of the heap. This at least causes the program to segmentation abort if the heap size parameter isn't aligned correctly. In version before GLIBC version 2.29 and aligned correctly, it allows arbitrary write anywhere in the programs memory.

Record
CVE-2021-40647
Updated
2026-11-02
EUVDEUVD-2021-27821 No score

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter in the top chunk of the heap. This at least causes the program to segmentation abort if the heap size parameter isn't aligned correctly. In version before GLIBC version 2.29 and aligned correctly, it allows arbitrary write anywhere in the programs memory.

Record
EUVD-2021-27821
Updated
2026-11-03
GitHub AdvisoriesGHSA-p3mv-74p6-4mgc 5.5

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter...

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter in the top chunk of the heap. This at least causes the program to segmentation abort if the heap size parameter isn't aligned correctly. In version before GLIBC version 2.29 and aligned correctly, it allows arbitrary write anywhere in the programs memory.

Record
GHSA-p3mv-74p6-4mgc
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-20
Updated
2026-11-02
OSV 5.5

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter in the top chunk of the heap. This at least causes the program to segmentation abort if the heap size parameter isn't aligned correctly. In version before GLIBC version 2.29 and aligned correctly, it allows arbitrary write anywhere in the programs memory.

Record
CVE-2021-40647
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
OSVDEBIAN-CVE-2021-40647 5.5

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter in the top chunk of the heap. This at least causes the program to segmentation abort if the heap size parameter isn't aligned correctly. In version before GLIBC version 2.29 and aligned correctly, it allows arbitrary write anywhere in the programs memory.

Record
DEBIAN-CVE-2021-40647
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
OSVUBUNTU-CVE-2021-40647 5.5

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter in the top chunk of the heap. This at least causes the program to segmentation abort if the heap size parameter isn't aligned correctly. In version before GLIBC version 2.29 and aligned correctly, it allows arbitrary write anywhere in the programs memory.

Record
UBUNTU-CVE-2021-40647
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-2025-0097 No score

Updated man2html packages fix security vulnerability

In man2html 1.6g, a specific string being read in from a file will overwrite the size parameter in the top chunk of the heap. This at least causes the program to segmentation abort if the heap size parameter isn't aligned correctly. In versions before GLIBC version 2.29 and if aligned correctly, it allows arbitrary writes anywhere in the program's memory.

Record
MGASA-2025-0097
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
man2html
Debian:12
All versions, plus listed versions
1.6g-141.6g-151.6g-16
None known
man2html
Debian:13
before 1.6g-16
1.6g-16
man2html
Debian:14
before 1.6g-16
1.6g-16
man2html
Mageia:9
before 1.6-6.1.mga9
1.6-6.1.mga9
man2html
Ubuntu:16.04:LTS
All versions, plus listed versions
1.6g-71.6g-8
None known
man2html
Ubuntu:18.04:LTS
All versions, plus listed versions
1.6g-91.6g-9ubuntu11.6g-11
None known
man2html
Ubuntu:20.04:LTS
All versions, plus listed versions
1.6g-12
None known
man2html
Ubuntu:22.04:LTS
All versions, plus listed versions
1.6g-14
None known
man2html
Ubuntu:24.04:LTS
All versions, plus listed versions
1.6g-141.6g-151.6g-16
None known
man2html
Ubuntu:25.10
All versions, plus listed versions
1.6g-16
None known
man2html
Ubuntu:26.10
All versions, plus listed versions
1.6g-16build1
None known
man2html
Ubuntu:26.04:LTS
All versions, plus listed versions
1.6g-161.6g-16build1
None known

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

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

In short

CVE-2021-40647 is a medium vulnerability (CVSS 5.5) in Man2html Project Man2html, published September 9, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.34%, the 27th percentile. Fixed in man2html 1.6g-16.

References

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