High
Security advisory
Go before 1.17 does not properly consider extraneous zero characters at the beginning of an IP address octet, which (in some situations) allows attackers to bypass access control that is based on IP addresses, because of unexpected octal interpretation. This affects net.ParseIP and net.ParseCIDR.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2021-29923
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 11:44 UTC · Revision 1
Source evidence
Go before 1.17 does not properly consider extraneous zero characters at the beginning of an IP address octet, which (in some situations) allows attackers to bypass access control that is based on IP addresses, because of unexpected octal interpretation. This affects net.ParseIP and net.ParseCIDR.
osv:CVE-2021-29923
Complete source record
{
"id": "8db16d77013f9923e5627f103dbcf24550970937c85db2e0fef1043c724df81b",
"url": "https://osv.dev/vulnerability/CVE-2021-29923",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2021-29923",
"summary": "Go before 1.17 does not properly consider extraneous zero characters at the beginning of an IP address octet, which (in some situations) allows attackers to bypass access control that is based on IP addresses, because of unexpected octal interpretation. This affects net.ParseIP and net.ParseCIDR.",
"evidence": "osv:CVE-2021-29923",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2021-29923",
"aliases": [
"BIT-golang-2021-29923",
"CVE-2021-29923"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/golang/go",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "ec5170397c724a8ae440b2bc529f857c86f0e6b1"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "1.17"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"go1.17rc2",
"go1.17rc1",
"go1.17beta1",
"go1.16beta1",
"go1.15beta1",
"go1.14beta1",
"go1.13beta1",
"go1.12beta2",
"go1.12beta1",
"go1.11beta3",
"go1.11beta2",
"go1.11beta1",
"go1.10rc2",
"go1.10rc1",
"go1.10beta2",
"go1.10beta1",
"go1.9beta2",
"go1.9beta1",
"go1.8beta2",
"go1.8beta1",
"go1.7rc4",
"go1.7rc3",
"go1.7rc2",
"go1.7rc1",
"go1.7beta2",
"go1.7beta1",
"go1.6beta2",
"go1.6beta1",
"go1.5beta3",
"go1.5beta2",
"go1.5beta1",
"go1.4beta1",
"go1.3beta2",
"go1.3beta1",
"weekly.2012-03-27",
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"weekly.2009-11-10",
"weekly.2009-11-06"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-29923.json"
}
}
],
"modified": "2026-10-20T10:54:38.916834638Z",
"provider": "osv",
"references": [
"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4CHKSFMHZVOBCZSSVRE3UEYNKARTBMTM/",
"https://defcon.org/html/defcon-29/dc-29-speakers.html#kaoudis",
"https://golang.org/pkg/net/#ParseCIDR",
"https://security.gentoo.org/glsa/202208-02",
"https://github.com/golang/go/issues/30999",
"https://github.com/golang/go/issues/43389",
"https://go-review.googlesource.com/c/go/+/325829/",
"https://www.oracle.com/security-alerts/cpujan2022.html",
"https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-016.md"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
"cpe:2.3:a:oracle:timesten_in-memory_database:*:*:*:*:*:*:*:*"
],
"vendor_product": "oracle:timesten_in-memory_database",
"extracted_events": [
{
"range": [
{
"fixed": "21.1.1.1.0"
}
],
"source": "CPE_RANGE"
}
]
},
{
"cpes": [
"cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:*"
],
"vendor_product": "fedoraproject:fedora",
"extracted_events": [
{
"range": [
{
"introduced": "36"
},
{
"last_affected": "36"
}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2021-29923",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 385798,
"published_at": "2021-08-07T17:15:07.067+00:00"
}