putty — security advisory
Multiple heap-based buffer overflows in the modpow function in PuTTY before 0.55 allow (1) remote attackers to execute arbitrary code via an SSH2 packet with a base argument that is larger than the mod argument, which causes the modpow function to write memory before the beginning of its buffer, and (2) remote malicious servers to cause a denial of service (client crash) and possibly execute arbitrary code via a large bignum during authentication.
- Products
- putty
- Affected versions
- Not specified
- Fixed versions
- 0.56-1
- CVEs
- CVE-2004-1440
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 14:25 UTC · Revision 1
Source evidence
Multiple heap-based buffer overflows in the modpow function in PuTTY before 0.55 allow (1) remote attackers to execute arbitrary code via an SSH2 packet with a base argument that is larger than the mod argument, which causes the modpow function to write memory before the beginning of its buffer, and (2) remote malicious servers to cause a denial of service (client crash) and possibly execute arbitrary code via a large bignum during authentication.
osv:DEBIAN-CVE-2004-1440
putty
Fixed versions: 0.56-1
putty
Fixed versions: 0.56-1
putty
Fixed versions: 0.56-1
Complete source record
{
"id": "fa26bf68d5d33f1772e4d0f76a67f7adc311d2962eff679f1710cc9b7abaf994",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2004-1440",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2004-1440",
"summary": "Multiple heap-based buffer overflows in the modpow function in PuTTY before 0.55 allow (1) remote attackers to execute arbitrary code via an SSH2 packet with a base argument that is larger than the mod argument, which causes the modpow function to write memory before the beginning of its buffer, and (2) remote malicious servers to cause a denial of service (client crash) and possibly execute arbitrary code via a large bignum during authentication.",
"evidence": "osv:DEBIAN-CVE-2004-1440",
"products": [
{
"name": {
"value": "putty",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "0.56-1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "putty",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "0.56-1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "putty",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "0.56-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
}
],
"severity": "unknown",
"structured": {
"id": "DEBIAN-CVE-2004-1440",
"aliases": [
"DEBIAN-CVE-2004-1440"
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "0.56-1"
}
]
}
],
"package": {
"name": "putty",
"purl": "pkg:deb/debian/putty?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2004-1440.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "0.56-1"
}
]
}
],
"package": {
"name": "putty",
"purl": "pkg:deb/debian/putty?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2004-1440.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "0.56-1"
}
]
}
],
"package": {
"name": "putty",
"purl": "pkg:deb/debian/putty?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2004-1440.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-21T15:47:34.944224995Z",
"provider": "osv",
"upstream": [
"CVE-2004-1440"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2004-1440"
]
},
"related_cves": [
{
"value": "CVE-2004-1440",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": null
},
"source_id": "core-osv",
"document_id": 394014,
"published_at": "2004-12-31T05:00:00+00:00"
}