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CVE-2021-45707

31
FAUCET Score

CVE-2021-45707 is a critical out-of-bounds write vulnerability affecting the nix crate versions 0.16.0 through 0.20.1, 0.21.x before 0.21.2, and 0.22.x before 0.22.2 for Rust. Specifically, the unistd::getgrouplist function can write beyond allocated memory if a user belongs to more than 16 groups in /etc/groups. This vulnerability carries a CVSS score of 9.8 (CRITICAL), indicating a severe risk due to its network-based attack vector, low attack complexity, and potential for complete compromise of confidentiality, integrity, and availability. Its FAUCET Risk Score is 79/100, further emphasizing its high severity. Currently, there is no evidence of active exploitation, nor are there publicly available exploit modules in Metasploit, Nuclei, or ExploitDB. Community discussion and media coverage for this CVE are minimal, which is typical for a large percentage of reported vulnerabilities.

Impacted Technologies

VendorProductVersion(s)CPE
>= 0.16.0, < 0.20.2CPE matchmatch criteria
cpe:2.3:a:nix_project:nix:*:*:*:*:*:rust:*:*
>= 0.21.0, < 0.21.2CPE matchmatch criteria
cpe:2.3:a:nix_project:nix:*:*:*:*:*:rust:*:*
>= 0.22.0, < 0.22.2CPE matchmatch criteria
cpe:2.3:a:nix_project:nix:*:*:*:*:*:rust:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.65%
Probability of exploitation in next 30 days
EPSS Percentile
74.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0165 is in the 62nd percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (9)

microsoftpatch availablevia msrc
Product: Azure Linux 3.0 ARMFixed in: 2024.4-1
microsoftpatch availablevia msrc
Product: azl3 rpm-ostree 2024.4-1 on Azure Linux 3.0Fixed in: 2024.4-1
microsoftpatch availablevia msrc
Product: azl3 rpm-ostree 2022.1-7 on Azure Linux 3.0Fixed in: 2024.4-1
microsoftpatch availablevia msrc
Product: Azure Linux 3.0 x64Fixed in: 2024.4-1
microsoftpatch availablevia msrc
Product: 17811-17084Fixed in: 2024.4-1
microsoftpatch availablevia msrc
Product: 18815-17084Fixed in: 2024.4-1
rustpatch availablevia ghsa
Product: nixFixed in: 0.22.2
rustpatch availablevia ghsa
Product: nixFixed in: 0.20.2
rustpatch availablevia ghsa
Product: nixFixed in: 0.21.2

Vendor Advisories (3)

microsoft2024-Sep/CVE-2021-45707

CVE-2021-45707

Sep 10, 2024
rustGHSA-76w9-p8mg-j927medium

Out-of-bounds Write in nix

Jan 6, 2022
microsoft2021-Dec/CVE-2021-45707Critical

An issue was discovered in the nix crate 0.16.0 and later before 0.20.2 0.21.x before 0.21.2 and 0.22.x before 0.22.2 for Rust. unistd::getgrouplist has an out-of-bounds write if a user is in more than 16 /etc/groups groups.

Dec 14, 2021

References

github.com / advisories/GHSA-wgrg-5h56-jg27
Third Party Advisory
raw.githubusercontent.com / rustsec/advisory-db/main/crates/nix/RUSTSEC-2021-0119.md
Third Party Advisory
rustsec.org / advisories/RUSTSEC-2021-0119.html
Issue TrackingThird Party Advisory