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CVE-2021-38189

29
FAUCET Score

CVE-2021-38189 describes a critical vulnerability in the Rust lettre crate prior to version 0.9.6, allowing attackers to inject arbitrary SMTP commands within an email message body. With a CVSS score of 9.8 (CRITICAL), this vulnerability presents a severe risk due to its network-based attack vector, low complexity, and potential for complete compromise of confidentiality, integrity, and availability. Currently, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.9.6CPE matchmatch criteria
cpe:2.3:a:lettre:lettre:*:*:*:*:*:rust:*:*
0.10.0CPE matchmatch criteria
cpe:2.3:a:lettre:lettre:0.10.0:alpha1:*:*:*:rust:*:*
0.10.0CPE matchmatch criteria
cpe:2.3:a:lettre:lettre:0.10.0:alpha2:*:*:*:rust:*:*
0.10.0CPE matchmatch criteria
cpe:2.3:a:lettre:lettre:0.10.0:alpha3:*:*:*:rust:*:*
0.10.0CPE matchmatch criteria
cpe:2.3:a:lettre:lettre:0.10.0:alpha4:*:*:*: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
1.49%
Probability of exploitation in next 30 days
EPSS Percentile
71.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0149 is in the 58th 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 (1)

rustpatch availablevia ghsa
Product: lettreFixed in: 0.9.6

Vendor Advisories (1)

rustGHSA-qc36-q22q-cjw3critical

SMTP command injection in lettre

Jul 12, 2021

References

raw.githubusercontent.com / rustsec/advisory-db/main/crates/lettre/RUSTSEC-2021-0069.md
Third Party Advisory
rustsec.org / advisories/RUSTSEC-2021-0069.html
ExploitIssue TrackingPatchThird Party Advisory