#VU56829 Input validation error in Go programming language - CVE-2021-29923

Vulnerability identifier: #VU56829

Vulnerability risk: Medium

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-29923

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Go programming language
Universal components / Libraries / Scripting languages

Vendor: Google

Description

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to insufficient validation of user-supplied input in net.ParseIP and net.ParseCIDR, as the Go interpreter does not properly consider extraneous zero characters at the beginning of an IP address octet. A remote attacker can bypass access control that is based on IP addresses, because of unexpected octal interpretation.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Go programming language: 1.14.15 - 1.16.7

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External links
https://github.com/golang/go/issues/43389
https://github.com/golang/go/issues/30999
https://defcon.org/html/defcon-29/dc-29-speakers.html#kaoudis
https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-016.md
https://golang.org/pkg/net/#ParseCIDR
https://go-review.googlesource.com/c/go/+/325829/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.