Go before 1.17 does not properly consider extraneous zero characters at the beginning of an IP address octet, which (in some situations) al…

published 2021-08-07 5 y ago modified 2026-09-08 2 mo ago also BIT-golang-2021-29923 , EUVD-2021-16397

cvss: 7.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 3.7%; EPSS 3.7% chance of exploitation in 30 days, percentile 89%
public exploits: 0; none known

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.

Patch / fix

fixed in 3 distros 4 links 2

bitnami golang 1.17.0
golang go 1.17
oracle timesten_in-memory_database 21.1.1.1.0

red hat rocky linux alpine arch linux

delve RHEL 8 1.5.0-2.module+el8.4.0+8864+58b0fcdb
golang RHEL 8 1.15.14-2.module+el8.4.0+12542+e3fec473
go-toolset RHEL 8 1.15.14-2.module+el8.4.0+12542+e3fec473
golang-bin RHEL 8 1.15.14-2.module+el8.4.0+12542+e3fec473
golang-src RHEL 8 1.15.14-2.module+el8.4.0+12542+e3fec473
golang-misc RHEL 8 1.15.14-2.module+el8.4.0+12542+e3fec473
golang-race RHEL 8 1.15.14-2.module+el8.4.0+12542+e3fec473
golang-tests RHEL 8 1.15.14-2.module+el8.4.0+12542+e3fec473

red hat advisories RHSA-2021:3585 RHSA-2022:1276 RHSA-2022:0989 RHSA-2022:0988 RHSA-2022:0997 RHSA-2022:0432

delve Rocky Linux 8 1.5.0-2.module+el8.4.0+396+d2d16ae3
golang Rocky Linux 8 1.15.14-2.module+el8.4.0+646+fc1a61b2
go-toolset Rocky Linux 8 1.15.14-2.module+el8.4.0+646+fc1a61b2

rocky linux advisories RLSA-2021:3585

go Alpine 3.24, Alpine 3.23, Alpine 3.22 +7 more 1.17-r0

alpine advisories ALPINE-CVE-2021-29923

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

go Arch Linux 2:1.17-1

arch linux advisories AVG-1357

oracle.com/security-alerts/cpujan2022.html advisory
go-review.googlesource.com/c/go/+/325829/ advisory

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-29923 updated 2026-11-07 cvss 7.3

golang: net: incorrect parsing of extraneous zero characters at the beginning of an IP address octet

Red Hat Migration Toolkit for Containers rhmtc/openshift-velero-plugin-rhel8, rhmtc/openshift-migration-velero-rhel8, rhmtc/openshift-migration-registry-rhel8, rhmtc/openshift-migration-must-gather-rhel8, rhmtc/openshift-migration-velero-restic-restore-helper-rhel8, rhmtc/openshift-migration-velero-plugin-for-microsoft-azure-rhel8 Red Hat OpenShift Serverless openshift-serverless-1/kn-eventing-apiserver-receive-adapter-rhel9 Red Hat OpenShift Service Mesh 2.0 servicemesh-grafana, servicemesh-operator, servicemesh-grafana-prometheus Red Hat Advanced Cluster Security 3 scanner
affected: workaround, no fix available
Red Hat Ceph Storage 2 golang, grafana, golang-bin, golang-src Red Hat Ceph Storage 3 golang, grafana, golang-bin, golang-src, grafana-container, prometheus-node-exporter
affected: workaround, no fix planned “Out of support scope”
Red Hat Ceph Storage 4 rhceph/rhceph-4-dashboard-rhel8
affected: workaround, no fix planned “Will not fix”
Red Hat Enterprise Linux 7 golang, buildah, golang-bin, golang-src, golang-misc, golang-tests Red Hat Enterprise Linux 8 buildah, buildah-tests
affected: workaround, no fix planned “Out of support scope”
Red Hat Enterprise Linux 9 buildah, buildah-tests
affected: workaround, no fix available
Red Hat OpenShift Container Platform 3.11 atomic-openshift, atomic-openshift-pod, atomic-openshift-node, atomic-openshift-tests, atomic-openshift-master, atomic-openshift-clients, +7 more
affected: workaround, no fix planned “Out of support scope”
Red Hat OpenShift Container Platform 4 podman, openshift, podman-tests, podman-docker, podman-remote, podman-gvproxy, +13 more
affected: workaround, no fix available “Fix deferred”
Red Hat OpenShift Container Platform Assisted Installer 1 rhai-tech-preview/assisted-installer-rhel8
affected: workaround, no fix available

show 20 more

Red Hat Openshift Container Storage 4 mcg, ocs4/cephcsi-rhel8, ocs4/mcg-rhel8-operator, ocs4/ocs-rhel8-operator
affected: workaround, no fix available, no fix planned “Will not fix”
Red Hat Openshift Sandboxed Containers openshift-sandboxed-containers/osc-rhel8-operator
affected: workaround, no fix available
Red Hat OpenShift Virtualization 2 virt-api-container, kubemacpool-container, virt-handler-container, bridge-marker-container, virt-launcher-container, virt-operator-container, +25 more Red Hat OpenShift Virtualization 4 container-native-virtualization/virt-api, container-native-virtualization/kubemacpool, container-native-virtualization/virt-handler, container-native-virtualization/bridge-marker, container-native-virtualization/virt-launcher, container-native-virtualization/virt-operator, +22 more
affected: workaround, no fix available, no fix planned “Will not fix”
Red Hat Quay 3 quay/quay-rhel8, quay/clair-rhel8, quay/quay-builder-rhel8, quay/quay-operator-rhel8, quay/quay-openshift-bridge-rhel8-operator, quay/quay-container-security-operator-rhel8
affected: workaround, no fix available
Red Hat Storage 3 etcd, golang, heketi, grafana, golang-bin, golang-src, +5 more
affected: workaround, no fix planned “Out of support scope”
Red Hat CNV 2.6 for RHEL 7 kubevirt 2.6.8-211.el7, kubevirt-virtctl 2.6.8-211.el7, kubevirt-virtctl-redistributable 2.6.8-211.el7 Red Hat CNV 2.6 for RHEL 8 kubevirt 2.6.8-211.el8, kubevirt-virtctl 2.6.8-211.el8, kubevirt-virtctl-redistributable 2.6.8-211.el8, container-native-virtualization/kubevirt-cpu-node-labeller v2.6.8-1
fixed: vendor fix RHSA-2021:4722
Red Hat CNV 4.8 for RHEL 7 kubevirt 4.8.3-251.el7, kubevirt-virtctl 4.8.3-251.el7, kubevirt-virtctl-redistributable 4.8.3-251.el7 Red Hat CNV 4.8 for RHEL 8 kubevirt 4.8.3-251.el8, kubevirt-virtctl 4.8.3-251.el8, kubevirt-virtctl-redistributable 4.8.3-251.el8
fixed: vendor fix RHSA-2021:4910
Red Hat OpenShift Service Mesh 2.0 servicemesh 2.0.9-3.el8, kiali v1.24.7.redhat1-1.el8, servicemesh-mixc 2.0.9-3.el8, servicemesh-mixs 2.0.9-3.el8, servicemesh-proxy 2.0.9-3.el8, servicemesh-istioctl 2.0.9-3.el8, +3 more
fixed: vendor fix RHSA-2022:1276
Red Hat Developer Tools for Red Hat Enterprise Linux Server (v. 7) go-toolset-1.15-golang 1.15.14-2.el7_9, go-toolset-1.15-golang-bin 1.15.14-2.el7_9, go-toolset-1.15-golang-src 1.15.14-2.el7_9, go-toolset-1.15-golang-misc 1.15.14-2.el7_9, go-toolset-1.15-golang-race 1.15.14-2.el7_9, go-toolset-1.15-golang-tests 1.15.14-2.el7_9 Red Hat Developer Tools for Red Hat Enterprise Linux Workstation (v. 7) go-toolset-1.15-golang 1.15.14-2.el7_9, go-toolset-1.15-golang-bin 1.15.14-2.el7_9, go-toolset-1.15-golang-src 1.15.14-2.el7_9, go-toolset-1.15-golang-misc 1.15.14-2.el7_9, go-toolset-1.15-golang-race 1.15.14-2.el7_9, go-toolset-1.15-golang-tests 1.15.14-2.el7_9
fixed: vendor fix RHSA-2021:3431
Red Hat Enterprise Linux AppStream (v. 8) delve 1.5.0-2.module+el8.4.0+8864+58b0fcdb, golang 1.15.14-2.module+el8.4.0+12542+e3fec473, go-toolset 1.15.14-2.module+el8.4.0+12542+e3fec473, golang-bin 1.15.14-2.module+el8.4.0+12542+e3fec473, golang-src 1.15.14-2.module+el8.4.0+12542+e3fec473, golang-misc 1.15.14-2.module+el8.4.0+12542+e3fec473, +2 more
fixed: vendor fix RHSA-2021:3585
Red Hat OpenShift Container Platform 4.9 cri-tools 1.22.0-2.el8, butane 0.13.1-2.rhaos4.9.el8, ignition 2.12.0-3.rhaos4.9.el8, cri-o 1.22.1-17.rhaos4.9.git3029b1d.el7, ignition-validate 2.12.0-3.rhaos4.9.el8, prometheus-promu 0.5.0-5.git642a960.el8, +144 more
fixed: vendor fix RHSA-2022:0557
Red Hat OpenShift Container Platform 4.10 openshift4-wincw/windows-machine-config-rhel8-operator 5.0.0-5, openshift4-wincw/windows-machine-config-operator-bundle v5.0.0-5
fixed: vendor fix RHSA-2022:0577
Red Hat OpenShift Serverless 1.0 openshift-serverless-clients 0.26.0-2.el8
fixed: vendor fix RHSA-2022:0432
Red Hat OpenShift Serverless 1.20 openshift-serverless-1/client-kn-rhel8 0.26.0-1, openshift-serverless-1/serving-queue-rhel8 0.26.0-1, openshift-serverless-1/eventing-mtping-rhel8 0.26.0-1, openshift-serverless-1/kourier-control-rhel8 0.26.0-1, openshift-serverless-1/serving-webhook-rhel8 0.26.0-1, openshift-serverless-1/eventing-webhook-rhel8 0.26.0-1, +28 more
fixed: vendor fix RHSA-2022:0434
Red Hat OpenStack Platform 16.1 etcd 3.3.23-7.el8ost, golang-qpid-apache 0.32.0-rc1.9.el8ost, golang-github-vbatts-tar-split 0.11.1-6.el8ost
fixed: vendor fix RHSA-2022:0260
Red Hat OpenStack Platform 16.2 etcd 3.3.23-7.el8ost, golang-qpid-apache 0.32.0-rc1.9.el8ost, golang-github-vbatts-tar-split 0.11.1-6.el8ost
fixed: vendor fix RHSA-2022:0237
Red Hat RHACS 3.67 for RHEL 8 advanced-cluster-security/rhacs-rhel8-operator 3.67.0-3
fixed: vendor fix RHSA-2021:4902
Red Hat RHACS 3.68 for RHEL 8 advanced-cluster-security/rhacs-scanner-rhel8 3.68.0-6
fixed: vendor fix RHSA-2022:0431
Red Hat RHODF 4.10 for RHEL 8 odf4/cephcsi-rhel8 v4.10.0-35, odf4/mcg-core-rhel8 v4.10.0-12, odf4/odf-console-rhel8 v4.10.0-27, odf4/odf-topolvm-rhel8 v4.10.0-16, odf4/mcg-rhel8-operator v4.10.0-14, odf4/ocs-rhel8-operator v4.10.0-58, +18 more
fixed: vendor fix RHSA-2022:1372
Red Hat CNV 2.6 for RHEL 8 container-native-virtualization/vm-import-controller v2.6.8-1, container-native-virtualization/vm-import-controller-rhel8 v2.6.8-1, container-native-virtualization/kubevirt-kvm-info-nfd-plugin v2.6.8-1, container-native-virtualization/kubevirt-cpu-model-nfd-plugin v2.6.8-2 Red Hat OpenShift Service Mesh 2.0 servicemesh-cni 2.0.9-3.el8, servicemesh-operator 2.0.9-3.el8 Red Hat Enterprise Linux 9 golang, go-toolset, golang-bin, golang-src, golang-misc, golang-race, +1 more Red Hat OpenShift Container Platform 4 openshift-clients
not affected: vulnerable code not present

10 more not affected in the full advisory

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.74% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/golang/go/issues/30999 referenced PoC, tagged "exploit" by a source, unverified
github.com https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-016.md referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:P/A:N
OSV	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem	package	affected	fixed in
bitnami	golang	<1.17.0	1.17.0

References

oracle.com /security-alerts/cpujan2022.html
patch, third-party-advisory, advisory
go-review.googlesource.com /c/go/+/325829/
patch, third-party-advisory, advisory
github.com /golang/go/issues/30999
exploit, issue-tracking, third-party-advisory, advisory
github.com /sickcodes/security/blob/master/advisories/SICK-2021-016.md
exploit, third-party-advisory, advisory
lists.fedoraproject.org /archives/list/package-announce%40lists.fedoraproject.org/message/4CHKSFMHZVOBCZSSVRE3UEYNKARTBMTM/
vendor-advisory, web
security.gentoo.org /glsa/202208-02
vendor-advisory, third-party-advisory, advisory
golang.org /pkg/net/#ParseCIDR
vendor-advisory, advisory
defcon.org /html/defcon-29/dc-29-speakers.html#kaoudis
third-party-advisory, advisory
github.com /golang/go/issues/43389
issue-tracking, third-party-advisory, advisory
nvd.nist.gov /vuln/detail/CVE-2021-29923
web

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary