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Fencer Vulns
critical 9.8

CVE-2021-38189 json

SMTP command injection in lettre

published 2021-05-22 5 y ago modified 2026-06-17 4 mo ago also GHSA-qc36-q22q-cjw3 , RUSTSEC-2021-0069 , EUVD-2021-1485

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

An issue was discovered in the lettre crate before 0.9.6 for Rust. In an e-mail message body, an attacker can place a . character after two <CR><LF> sequences and then inject arbitrary SMTP commands.

Patch / fix

  • crates.io lettre 0.9.6, 0.10.0-rc.3
  • lettre lettre 0.9.6

Exploit prediction

1.49% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • rustsec.org https://rustsec.org/advisories/RUSTSEC-2021-0069.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
crates.io lettre
>=0.7.0, <0.9.6
>=0.10.0-alpha.1, <0.10.0-rc.3
0.9.6
0.10.0-rc.3

Classification

Weakness
  • CWE-77 Improper Neutralization of Special Elements used in a Command
  • CWE-147 Improper Neutralization of Input Terminators

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.