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CVE-2021-38196

30
FAUCET Score

CVE-2021-38196 describes a critical vulnerability in the Rust better-macro crate, affecting better_macro_project and better_macro. This intentionally created vulnerability allows remote attackers to execute arbitrary code through proc-macros. With a CVSS score of 9.8 (CRITICAL), it presents a severe risk due to its network-based attack vector, low attack complexity, and high impact on confidentiality, integrity, and availability. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2021-07-22CPE matchmatch criteria
cpe:2.3:a:better-macro_project:better-macro:*:*:*:*:*: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
2.57%
Probability of exploitation in next 30 days
EPSS Percentile
83.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0257 is in the 74th percentile among its peer group of 36,897 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

Vendor Advisories (1)

rustGHSA-79wf-qcqv-r22rhigh

Remote code execution in better-macro

Aug 25, 2021

References

raw.githubusercontent.com / rustsec/advisory-db/main/crates/better-macro/RUSTSEC-2021-0077.md
Third Party Advisory
rustsec.org / advisories/RUSTSEC-2021-0077.html
ExploitIssue TrackingPatchThird Party Advisory