Medium
man2html — security advisory
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.
- Products
- man2html
- Affected versions
- 1.6g-11, 1.6g-12, 1.6g-14, 1.6g-15, 1.6g-16, 1.6g-16build1, 1.6g-7, 1.6g-8, 1.6g-9, 1.6g-9ubuntu1
- Fixed versions
- Not specified
- CVEs
- CVE-2021-40647
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 01:00 UTC · Revision 1
Source evidence
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.
osv:UBUNTU-CVE-2021-40647
man2html
Fixed versions: Not specified
man2html
Fixed versions: Not specified
man2html
Fixed versions: Not specified
man2html
Fixed versions: Not specified
man2html
Fixed versions: Not specified
man2html
Fixed versions: Not specified
man2html
Fixed versions: Not specified
man2html
Fixed versions: Not specified
Complete source record
{
"id": "1cee7ba2ad56fd2cdbe072de9e9bc9cad208d239563f747c93688ce5dce6136e",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2021-40647",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2021-40647",
"summary": "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.",
"evidence": "osv:UBUNTU-CVE-2021-40647",
"products": [
{
"name": {
"value": "man2html",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.6g-7",
"evidence": "/affected/0/versions"
},
{
"value": "1.6g-8",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "man2html",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.6g-9",
"evidence": "/affected/1/versions"
},
{
"value": "1.6g-9ubuntu1",
"evidence": "/affected/1/versions"
},
{
"value": "1.6g-11",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "man2html",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.6g-12",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "man2html",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.6g-14",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "man2html",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.6g-14",
"evidence": "/affected/4/versions"
},
{
"value": "1.6g-15",
"evidence": "/affected/4/versions"
},
{
"value": "1.6g-16",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "man2html",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.6g-16",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "man2html",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.6g-16build1",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "man2html",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.6g-16",
"evidence": "/affected/7/versions"
},
{
"value": "1.6g-16build1",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2021-40647",
"aliases": [
"UBUNTU-CVE-2021-40647"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "man2html",
"purl": "pkg:deb/ubuntu/man2html?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"1.6g-7",
"1.6g-8"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40647.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "man2html",
"binary_version": "1.6g-8"
},
{
"binary_name": "man2html-base",
"binary_version": "1.6g-8"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "man2html",
"purl": "pkg:deb/ubuntu/man2html?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"1.6g-9",
"1.6g-9ubuntu1",
"1.6g-11"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40647.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "man2html",
"binary_version": "1.6g-11"
},
{
"binary_name": "man2html-base",
"binary_version": "1.6g-11"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "man2html",
"purl": "pkg:deb/ubuntu/man2html?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"1.6g-12"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40647.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "man2html",
"binary_version": "1.6g-12"
},
{
"binary_name": "man2html-base",
"binary_version": "1.6g-12"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "man2html",
"purl": "pkg:deb/ubuntu/man2html?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"1.6g-14"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40647.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "man2html",
"binary_version": "1.6g-14"
},
{
"binary_name": "man2html-base",
"binary_version": "1.6g-14"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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}
]
}
],
"package": {
"name": "man2html",
"purl": "pkg:deb/ubuntu/man2html?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"1.6g-14",
"1.6g-15",
"1.6g-16"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40647.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "man2html",
"binary_version": "1.6g-16"
},
{
"binary_name": "man2html-base",
"binary_version": "1.6g-16"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
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{
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}
]
}
],
"package": {
"name": "man2html",
"purl": "pkg:deb/ubuntu/man2html?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"1.6g-16"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40647.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "man2html",
"binary_version": "1.6g-16"
},
{
"binary_name": "man2html-base",
"binary_version": "1.6g-16"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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}
]
}
],
"package": {
"name": "man2html",
"purl": "pkg:deb/ubuntu/man2html?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"1.6g-16build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40647.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "man2html",
"binary_version": "1.6g-16build1"
},
{
"binary_name": "man2html-base",
"binary_version": "1.6g-16build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "man2html",
"purl": "pkg:deb/ubuntu/man2html?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.6g-16",
"1.6g-16build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-40647.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "man2html",
"binary_version": "1.6g-16build1"
},
{
"binary_name": "man2html-base",
"binary_version": "1.6g-16build1"
}
]
}
}
],
"modified": "2026-10-17T12:56:20.736431079Z",
"provider": "osv",
"upstream": [
"CVE-2021-40647"
],
"references": [
"https://ubuntu.com/security/CVE-2021-40647",
"https://gist.github.com/untaman/cb58123fe89fc65e3984165db5d40933",
"https://www.cve.org/CVERecord?id=CVE-2021-40647"
]
},
"related_cves": [
{
"value": "CVE-2021-40647",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 355349,
"published_at": "2022-09-09T18:15:00+00:00"
}