Critical
Security advisory
Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in which an unauthenticated remote attacker can execute arbitrary code by leveraging the mishandling of continuation lines during header-length restriction.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2020-28020
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 09:26 UTC · Revision 1
Source evidence
Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in which an unauthenticated remote attacker can execute arbitrary code by leveraging the mishandling of continuation lines during header-length restriction.
osv:CVE-2020-28020
Complete source record
{
"id": "5ac32574520231cd850e3907f8fb73a92654abf8a10666d77b1073c0f95ab925",
"url": "https://osv.dev/vulnerability/CVE-2020-28020",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2020-28020",
"summary": "Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in which an unauthenticated remote attacker can execute arbitrary code by leveraging the mishandling of continuation lines during header-length restriction.",
"evidence": "osv:CVE-2020-28020",
"products": [],
"severity": "critical",
"structured": {
"id": "CVE-2020-28020",
"aliases": [
"CVE-2020-28020"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/exim/exim",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "ae63862ba6f6ee0c17ec865cc6cf0eebb3ca2389"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "4.00"
},
{
"fixed": "4.92"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"exim-4.92-RC5",
"exim-4.92-RC4",
"exim-4.92-RC3",
"exim-4.92-RC2",
"exim-4.92-RC1",
"exim-4_91",
"exim-4_91_RC4",
"exim-4_91_RC3",
"exim-4_91_RC2",
"exim-4_91_RC1",
"exim-4_90_RC4",
"exim-4_90",
"exim-4_90_RC3",
"exim-4_90_RC2",
"exim-4_90_RC1",
"exim-4.90devstart",
"exim-4_89_RC3",
"exim-4_89_RC1",
"exim-4_88",
"exim-4_87",
"exim-4_88_RC6",
"exim-4_88_RC5",
"exim-4_88_RC4",
"exim-4_88_RC3",
"exim-4_88_RC2",
"exim-4_88_RC1",
"exim-4_87_RC7",
"exim-4_87_RC6",
"exim-4_87_RC5",
"exim-4_87_RC4",
"exim-4_84",
"exim-4_86",
"exim-4_85",
"exim-4_87_RC3",
"exim-4_87_RC2",
"exim-4_87_RC1",
"exim-4_86_RC5",
"exim-4_86_RC4",
"exim-4_86_RC3",
"exim-4_86_RC2",
"exim-4_86_RC1",
"exim-4_85_RC4",
"exim-4_85_RC3",
"exim-4_85_RC2",
"exim-4_85_RC1",
"exim-4_84_RC2",
"exim-4_84_RC1",
"exim-4_83",
"exim-4_83_RC3",
"exim-4_83_RC2",
"exim-4_83_RC1",
"exim-4_82",
"exim-4_82_RC5",
"exim-4_82_RC4",
"exim-4_82_RC3",
"exim-4_82_RC2",
"exim-4_82_RC1",
"exim-4_80",
"exim-4_80_RC7",
"exim-4_80_RC6",
"exim-4_80_RC5",
"exim-4_80_RC4",
"exim-4_80_RC3",
"exim-4_80_RC2",
"exim-4_80_RC1",
"exim-4_77",
"exim-4_77_RC4",
"exim-4_77_RC3",
"exim-4_77_RC2",
"exim-4_77_RC1",
"exim-4_76",
"exim-4_76_RC2",
"exim-4_76_RC1",
"exim-4_75",
"exim-4_75_RC3",
"exim-4_75_RC2",
"exim-4_75_RC1",
"exim-4_74",
"exim-4_74_RC1",
"exim-4_73",
"exim-4_73_RC1",
"exim-4_73_RC00",
"exim-4_72",
"exim-4_72_RC2",
"exim-4_72_RC1",
"exim-4_71",
"exim-4_70",
"exim-4_70_RC4",
"exim-4_70_RC3",
"DEVEL_PDKIM_START",
"exim-4_69",
"exim-4_68",
"exim-4_67",
"exim-4_66",
"exim-4_65",
"exim-4_64",
"exim-4_63",
"exim-4_62",
"exim-4_61",
"exim-4_54",
"exim-4_53",
"exim-4_52",
"exim-4_51",
"exim-4_50"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-28020.json",
"vanir_signatures": [
{
"id": "CVE-2020-28020-1522f0d7",
"digest": {
"threshold": 0.9,
"line_hashes": [
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]
},
"source": "https://github.com/exim/exim/commit/ae63862ba6f6ee0c17ec865cc6cf0eebb3ca2389",
"target": {
"file": "src/src/smtp_in.c"
},
"deprecated": false,
"signature_type": "Line",
"signature_version": "v1"
},
{
"id": "CVE-2020-28020-32bbe9ef",
"digest": {
"length": 2856,
"function_hash": "24326669637228286557130795243383876882"
},
"source": "https://github.com/exim/exim/commit/ae63862ba6f6ee0c17ec865cc6cf0eebb3ca2389",
"target": {
"file": "src/src/smtp_in.c",
"function": "smtp_reset"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
}
],
"vanir_signatures_modified": "2026-10-24T14:22:43Z"
}
}
],
"modified": "2026-10-24T14:22:43.974046545Z",
"provider": "osv",
"references": [
"https://www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28020-HSIZE.txt"
],
"provider_metadata": {}
},
"related_cves": [
{
"value": "CVE-2020-28020",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 443689,
"published_at": "2021-05-06T13:15:09.613+00:00"
}