Critical
isync — security advisory
A flaw was found in mbsync in isync 1.4.0 through 1.4.3. Due to an unchecked condition, a malicious or compromised IMAP server could use a crafted mail message that lacks headers (i.e., one that starts with an empty line) to provoke a heap overflow, which could conceivably be exploited for remote code execution.
- Products
- isync
- Affected versions
- 1.1.2-1, 1.3.0-2.2, 1.4.3-1, 1.4.4-1, 1.4.4-3, 1.4.4-3ubuntu0.22.04.1, 1.4.4-5, 1.4.4-5build2, 1.4.4-5build3, 1.5.1-1ubuntu1, 1.5.1-1ubuntu2, 1.5.1-1ubuntu4
- Fixed versions
- Not specified
- CVEs
- CVE-2021-44143
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 00:44 UTC · Revision 1
Source evidence
A flaw was found in mbsync in isync 1.4.0 through 1.4.3. Due to an unchecked condition, a malicious or compromised IMAP server could use a crafted mail message that lacks headers (i.e., one that starts with an empty line) to provoke a heap overflow, which could conceivably be exploited for remote code execution.
osv:UBUNTU-CVE-2021-44143
isync
Fixed versions: Not specified
isync
Fixed versions: Not specified
isync
Fixed versions: Not specified
isync
Fixed versions: Not specified
isync
Fixed versions: Not specified
isync
Fixed versions: Not specified
Complete source record
{
"id": "a57b40843e0e82569d7d8242f7296b798e681e5830caaa988b1d9170f2aeeb4c",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2021-44143",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2021-44143",
"summary": "A flaw was found in mbsync in isync 1.4.0 through 1.4.3. Due to an unchecked condition, a malicious or compromised IMAP server could use a crafted mail message that lacks headers (i.e., one that starts with an empty line) to provoke a heap overflow, which could conceivably be exploited for remote code execution.",
"evidence": "osv:UBUNTU-CVE-2021-44143",
"products": [
{
"name": {
"value": "isync",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.1.2-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
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"evidence": "/affected/1/package/name"
},
"prerequisites": [],
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"affected_versions": [
{
"value": "1.3.0-2.2",
"evidence": "/affected/1/versions"
},
{
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"evidence": "/affected/1/versions"
},
{
"value": "1.4.4-1",
"evidence": "/affected/1/versions"
},
{
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"evidence": "/affected/1/versions"
},
{
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{
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{
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"evidence": "/affected/2/versions"
},
{
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}
]
},
{
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"evidence": "/affected/3/package/name"
},
"prerequisites": [],
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"affected_versions": [
{
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"evidence": "/affected/3/versions"
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{
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"evidence": "/affected/3/versions"
}
]
},
{
"name": {
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"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.5.1-1ubuntu2",
"evidence": "/affected/4/versions"
},
{
"value": "1.5.1-1ubuntu4",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
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"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.5.1-1ubuntu1",
"evidence": "/affected/5/versions"
},
{
"value": "1.5.1-1ubuntu2",
"evidence": "/affected/5/versions"
}
]
}
],
"severity": "critical",
"structured": {
"id": "UBUNTU-CVE-2021-44143",
"aliases": [
"UBUNTU-CVE-2021-44143"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
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"purl": "pkg:deb/ubuntu/isync?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"1.1.2-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-44143.json"
},
"ecosystem_specific": {
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{
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"binary_version": "1.1.2-1"
}
]
}
},
{
"ranges": [
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"package": {
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"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
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"ecosystem_specific": {
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{
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},
"versions": [
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"1.4.4-5build2",
"1.4.4-5build3"
],
"database_specific": {
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},
"ecosystem_specific": {
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{
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}
]
}
},
{
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},
"versions": [
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"1.5.1-1ubuntu1"
],
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},
"ecosystem_specific": {
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},
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"1.5.1-1ubuntu4"
],
"database_specific": {
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},
"ecosystem_specific": {
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{
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},
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"1.5.1-1ubuntu2"
],
"database_specific": {
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},
"ecosystem_specific": {
"binaries": [
{
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"binary_version": "1.5.1-1ubuntu2"
}
]
}
}
],
"modified": "2026-10-17T12:56:01.663986639Z",
"provider": "osv",
"upstream": [
"CVE-2021-44143"
],
"references": [
"https://ubuntu.com/security/CVE-2021-44143",
"https://sourceforge.net/p/isync/isync/commit_browser",
"https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=999804",
"https://sourceforge.net/p/isync/isync/ref/master/tags/",
"https://www.cve.org/CVERecord?id=CVE-2021-44143"
]
},
"related_cves": [
{
"value": "CVE-2021-44143",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 354612,
"published_at": "2021-11-22T20:15:00+00:00"
}