CVE-2021-29922

Name: CVE-2021-29922
Creator: NVD / NIST
Published: 2021-08-07T17:15:06.907+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.1/10EPSS 2.62%

Last modified Jun 17, 2026

CVE-2021-29922 is a critical-severity vulnerability rated 9.1/10 on the CVSS scale. library/std/src/net/parser.rs in Rust before 1.53.0 does not properly consider extraneous zero characters at the beginning of an IP address string, which (in some situations) allows attackers to bypass access control that is based on IP addresses, because of unexpected octal interpretation.. EPSS estimates a 2.62% chance of exploitation in the next 30 days.

Description

library/std/src/net/parser.rs in Rust before 1.53.0 does not properly consider extraneous zero characters at the beginning of an IP address string, which (in some situations) allows attackers to bypass access control that is based on IP addresses, because of unexpected octal interpretation.

Metrics

CVSS 3.1

9.1/10

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

EPSS Probability

2.62%

83.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Rust-Lang	Rust	< 1.53.0

References

https://defcon.org/html/defcon-29/dc-29-speakers.html#kaoudisThird Party Advisory
https://doc.rust-lang.org/beta/std/net/struct.Ipv4Addr.htmlVendor Advisory
https://github.com/rust-lang/rust/issues/83648Exploit, Issue Tracking, Patch, Third Party Advisory
https://github.com/rust-lang/rust/pull/83652Patch, Third Party Advisory
https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-015.mdExploit, Third Party Advisory
https://security.gentoo.org/glsa/202210-09Third Party Advisory
https://defcon.org/html/defcon-29/dc-29-speakers.html#kaoudisThird Party Advisory
https://doc.rust-lang.org/beta/std/net/struct.Ipv4Addr.htmlVendor Advisory
https://github.com/rust-lang/rust/issues/83648Exploit, Issue Tracking, Patch, Third Party Advisory
https://github.com/rust-lang/rust/pull/83652Patch, Third Party Advisory
https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-015.mdExploit, Third Party Advisory
https://security.gentoo.org/glsa/202210-09Third Party Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2021-29922?

How severe is CVE-2021-29922?

CVE-2021-29922 has a CVSS score of 9.1/10 (CRITICAL severity). The EPSS model estimates a 2.62% probability of exploitation in the next 30 days.

How do I fix CVE-2021-29922?

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-2021-29922?

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

Scan your code now

Source: NVD / NIST