CVE-2021-29923

Name: CVE-2021-29923
Creator: NVD / NIST
Published: 2021-08-07T17:15:07.067+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 3.74%

Last modified Jun 17, 2026

CVE-2021-29923 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.. EPSS estimates a 3.74% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS Probability

3.74%

88.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Golang	Go	< 1.17
Oracle	Timesten In-Memory Database	< 21.1.1.1.0
Fedoraproject	Fedora	36

References

https://defcon.org/html/defcon-29/dc-29-speakers.html#kaoudisThird Party Advisory
https://github.com/golang/go/issues/30999Exploit, Issue Tracking, Third Party Advisory
https://github.com/golang/go/issues/43389Issue Tracking, Third Party Advisory
https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-016.mdExploit, Third Party Advisory
https://go-review.googlesource.com/c/go/+/325829/Patch, Third Party Advisory
https://golang.org/pkg/net/#ParseCIDRVendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4CHKSFMHZVOBCZSSVRE3UEYNKARTBMTM/
https://security.gentoo.org/glsa/202208-02Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
https://defcon.org/html/defcon-29/dc-29-speakers.html#kaoudisThird Party Advisory
https://github.com/golang/go/issues/30999Exploit, Issue Tracking, Third Party Advisory
https://github.com/golang/go/issues/43389Issue Tracking, Third Party Advisory
https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-016.mdExploit, Third Party Advisory
https://go-review.googlesource.com/c/go/+/325829/Patch, Third Party Advisory
https://golang.org/pkg/net/#ParseCIDRVendor Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4CHKSFMHZVOBCZSSVRE3UEYNKARTBMTM/
https://security.gentoo.org/glsa/202208-02Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory

Timeline

Published: Aug 7, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-29923?

How severe is CVE-2021-29923?

CVE-2021-29923 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 3.74% probability of exploitation in the next 30 days.

How do I fix CVE-2021-29923?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-29923?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST