CVE-2020-28247: Lettre Argument Injection Vulnerability

MODERATE
Advisory Identifier: GHSA-vc2p-r46x-m3vx
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CVSS 5.3
CWE-77
Published
Advisory Summary

CVE-2020-28247 is a MODERATE (CVSS 5.3) argument injection vulnerability (CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection')) affecting Lettre libraries in the crates.io ecosystem. The issue involves argument injection in lettre. Remediation is available by upgrading affected packages to version 0.9.5, 0.8.4, 0.7.1.

CVE-2020-28247 at a Glance

CVE Identifier CVE-2020-28247
GHSA Identifier GHSA-vc2p-r46x-m3vx
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection')
Affected Product Lettre
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 5.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2020-28247

To remediate this vulnerability, upgrade all affected Lettre dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

lettre fixed: 0.9.5 
Upgrade lettre to 0.9.5
lettre fixed: 0.8.4 
Upgrade lettre to 0.8.4
lettre fixed: 0.7.1 
Upgrade lettre to 0.7.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for lettre

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-28247, inspect your project dependencies for Lettre:

inspect dependencies for lettre

Analyze the terminal output to locate any version of Lettre in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.9.5), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection'), where the product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component. In Lettre, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Affected versions of lettre allowed argument injection to the sendmail command. It was possible, using forged to addresses, to pass arbitrary arguments to the sendmail executable. Depending on the implementation (original sendmail, postfix, exim, etc.) it could be possible in some cases to write email data into abritrary files (using sendmail's logging features). *NOTE*: This vulnerability only affects the sendmail transport. Others, including smtp, are not affected. ### Fix The flaw is corrected by modifying the executed command to stop parsing arguments before passing the destination addresses. ### References * [RUSTSEC-2020-0069](https://rustsec.org/advisories/RUSTSEC-2020-0069.html) * [CVE-2020-28247](https://nvd.nist.gov/vuln/detail/CVE-2020-28247)

CVE-2020-28247 Affected Lettre Versions

3 component(s)
Fixed Versions:
0.9.50.8.40.7.1
Product / Package Ecosystem Affected Versions Fixed Version
lettre
 crates.io
≥ 0.9.0
< 0.9.5
0.9.5
lettre
 crates.io
≥ 0.8.0
< 0.8.4
0.8.4
lettre
 crates.io
≥ 0.7.0
< 0.7.1
0.7.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/lettre/lettre/security/advisories/GHSA-vc2p-r46x-m3vx
NVD — CVE-2020-28247 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-28247
Lettre Source Repository REPOSITORY
https://github.com/RustSec/advisory-db/pull/478/files
Lettre Source Repository REPOSITORY
https://github.com/lettre/lettre/pull/508/commits/bbe7cc5381c5380b54fb8bbb4f77a3725917ff0b
Lettre Source Repository REPOSITORY
https://github.com/lettre/lettre
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2020-0069.html

Frequently Asked Questions

What is CVE-2020-28247?
CVE-2020-28247 is a security vulnerability in Lettre involving Argument injection in lettre under CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection').
Which Lettre versions are affected?
Affected versions include releases prior to 0.9.5, 0.8.4, 0.7.1 across affected packages: lettre.
What version fixes CVE-2020-28247?
Upgrading to 0.9.5, 0.8.4, 0.7.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is lettre affected?
Yes, lettre is affected in releases prior to 0.9.5, 0.8.4, 0.7.1. Upgrade your dependency to 0.9.5, 0.8.4, 0.7.1 or later.
What is the CVSS score of CVE-2020-28247?
CVE-2020-28247 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2020-28247?
CVE-2020-28247 is classified under CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection') (The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.).
How can I check crates.io dependencies for CVE-2020-28247?
Run the dependency tree command: 'inspect dependencies for lettre'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-vc2p-r46x-m3vx",
  "modified" : "2021-08-18T20:59:57Z",
  "published" : "2021-08-25T20:56:48Z",
  "aliases" : [ "CVE-2020-28247" ],
  "summary" : "Argument injection in lettre",
  "details" : "### Impact\n\nAffected versions of lettre allowed argument injection to the sendmail command. It was possible, using forged to addresses, to pass arbitrary arguments to the sendmail executable.\n\nDepending on the implementation (original sendmail, postfix, exim, etc.) it could be possible in some cases to write email data into abritrary files (using sendmail's logging features).\n\n*NOTE*: This vulnerability only affects the sendmail transport. Others, including smtp, are not affected.\n\n### Fix\n\nThe flaw is corrected by modifying the executed command to stop parsing arguments before passing the destination addresses.\n\n### References\n\n* [RUSTSEC-2020-0069](https://rustsec.org/advisories/RUSTSEC-2020-0069.html)\n* [CVE-2020-28247](https://nvd.nist.gov/vuln/detail/CVE-2020-28247)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "lettre"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.9.0"
      }, {
        "fixed" : "0.9.5"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "lettre"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.8.0"
      }, {
        "fixed" : "0.8.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "lettre"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.7.0"
      }, {
        "fixed" : "0.7.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/lettre/lettre/security/advisories/GHSA-vc2p-r46x-m3vx"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-28247"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/RustSec/advisory-db/pull/478/files"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/lettre/lettre/pull/508/commits/bbe7cc5381c5380b54fb8bbb4f77a3725917ff0b"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/lettre/lettre"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2020-0069.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-77" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-18T20:59:57Z",
    "nvd_published_at" : null
  }
}