CVE-2021-29923 Security feature bypass in n/a

High 7.5 Published 7 Aug 2021 Updated 3 Aug 2024

Attackers can bypass IP-based access controls by using leading zeros in IP addresses, affecting Go applications using net.ParseIP or net.ParseCIDR.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2021-29923?

CVE-2021-29923 is a high-severity vulnerability in Fedoraproject Fedora, published on 7 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

Which versions are affected by CVE-2021-29923?

1 open source package ship an affected version, including golang. It affects 3 products.

Package	Affected	Fixed in
`golang` Bitnami	All versions	`1.17.0`

Linux distribution packages (22)

`kubevirt` Red Hat:container_native_virtualization:4.8::el7	All versions	`0:4.8.3-251.el7`
`kubevirt-virtctl` Red Hat:container_native_virtualization:4.8::el7	All versions	`0:4.8.3-251.el7`
`kubevirt-virtctl-redistributable` Red Hat:container_native_virtualization:4.8::el7	All versions	`0:4.8.3-251.el7`
`kubevirt` Red Hat:container_native_virtualization:4.8::el8	All versions	`0:4.8.3-251.el8`
`kubevirt-virtctl` Red Hat:container_native_virtualization:4.8::el8	All versions	`0:4.8.3-251.el8`
`kubevirt-virtctl-redistributable` Red Hat:container_native_virtualization:4.8::el8	All versions	`0:4.8.3-251.el8`
`delve` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.5.0-2.module+el8.4.0+8864+58b0fcdb`
`delve-debuginfo` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.5.0-2.module+el8.4.0+8864+58b0fcdb`
`delve-debugsource` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.5.0-2.module+el8.4.0+8864+58b0fcdb`
`go-toolset` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.15.14-2.module+el8.4.0+12542+e3fec473`
`golang` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.15.14-2.module+el8.4.0+12542+e3fec473`
`golang-bin` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.15.14-2.module+el8.4.0+12542+e3fec473`
`golang-docs` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.15.14-2.module+el8.4.0+12542+e3fec473`
`golang-misc` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.15.14-2.module+el8.4.0+12542+e3fec473`
`golang-race` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.15.14-2.module+el8.4.0+12542+e3fec473`
`golang-src` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.15.14-2.module+el8.4.0+12542+e3fec473`
`golang-tests` Red Hat:enterprise_linux:8::appstream	All versions	`0:1.15.14-2.module+el8.4.0+12542+e3fec473`
`golang-qpid-apache` Red Hat:openstack:16.1::el8	All versions	`0:0.32.0-rc1.9.el8ost`
`golang-qpid-apache` Red Hat:openstack:16.2::el8	All versions	`0:0.32.0-rc1.9.el8ost`
`delve` Rocky Linux:8	All versions	`0:1.5.0-2.module+el8.4.0+396+d2d16ae3`
`go-toolset` Rocky Linux:8	All versions	`0:1.15.14-2.module+el8.4.0+646+fc1a61b2`
`golang` Rocky Linux:8	All versions	`0:1.15.14-2.module+el8.4.0+646+fc1a61b2`

Products include Fedoraproject Fedora, Golang Go, Oracle Timesten In-Memory Database.

How do I fix CVE-2021-29923?

Upgrade golang to 1.17.0 or later.

Is CVE-2021-29923 being exploited?

There is no known exploitation of CVE-2021-29923 in the wild and no public exploit code.

All Fedoraproject Fedora vulnerabilities

Sources

Also known as AZL-79056, AZL-98910, BIT-golang-2021-29923, DEBIAN-CVE-2021-29923, GHSA-38h6-vxp4-qxvm, RHSA-2021:3585 and 5 more.