CVE-2021-40647
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.
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
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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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
| Package | Affected | Fixed |
|---|---|---|
man2htmlDebian:12 |
All versions, plus listed versions 1.6g-141.6g-151.6g-16 |
None known |
man2htmlDebian:13 |
before 1.6g-16 | 1.6g-16 |
man2htmlDebian:14 |
before 1.6g-16 | 1.6g-16 |
man2htmlMageia:9 |
before 1.6-6.1.mga9 | 1.6-6.1.mga9 |
man2htmlUbuntu:16.04:LTS |
All versions, plus listed versions 1.6g-71.6g-8 |
None known |
man2htmlUbuntu:18.04:LTS |
All versions, plus listed versions 1.6g-91.6g-9ubuntu11.6g-11 |
None known |
man2htmlUbuntu:20.04:LTS |
All versions, plus listed versions 1.6g-12 |
None known |
man2htmlUbuntu:22.04:LTS |
All versions, plus listed versions 1.6g-14 |
None known |
man2htmlUbuntu:24.04:LTS |
All versions, plus listed versions 1.6g-141.6g-151.6g-16 |
None known |
man2htmlUbuntu:25.10 |
All versions, plus listed versions 1.6g-16 |
None known |
man2htmlUbuntu:26.10 |
All versions, plus listed versions 1.6g-16build1 |
None known |
man2htmlUbuntu:26.04:LTS |
All versions, plus listed versions 1.6g-161.6g-16build1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE 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.