CVE-2026-90467
Received Received - Intake

aiosmtplib Email Address Injection Vulnerability

Publication date: 2026-09-12

Last updated on: 2026-09-12

Assigner: VulnCheck

Description
aiosmtplib before 5.1.3 fails to properly validate email addresses supplied by callers, allowing attackers to inject ESMTP parameters into MAIL FROM and RCPT TO command lines. Attackers can craft malicious addresses containing spaces and angle brackets to append parameters like AUTH, NOTIFY, or ORCPT to envelope commands, forging authenticated identities or forcing delivery notifications to third parties.

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Meta Information

Published
2026-09-12
Last Modified
2026-09-12
Generated
2026-09-12
AI Q&A
2026-09-12
EPSS Evaluated
N/A
NVD
CVE-2026-90467
EUVD
EUVD-2026-76774

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
cole aiosmtplib to 5.1.3 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-88 The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.

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Executive Summary

aiosmtplib before 5.1.3 fails to properly validate email addresses, allowing attackers to inject ESMTP parameters into MAIL FROM and RCPT TO commands. Malicious addresses with spaces or angle brackets can append parameters like AUTH or NOTIFY, enabling identity forgery or forcing delivery notifications to third parties.

Detection Guidance

To detect this vulnerability, check if your system uses aiosmtplib versions before 5.1.3. Run: pip show aiosmtplib. If installed, verify version with: python -c "import aiosmtplib; print(aiosmtplib.__version__)". If version is less than 5.1.3, the system is vulnerable.

Impact Analysis

Attackers could forge authenticated identities, redirect delivery notifications to unintended recipients, or manipulate SMTP commands. This may lead to unauthorized email sending, data leaks, or service disruptions if exploited in applications using vulnerable aiosmtplib versions.

Compliance Impact

This vulnerability could violate data integrity and confidentiality requirements in GDPR and HIPAA. Unauthorized email manipulation may lead to unauthorized data access or disclosure, potentially resulting in non-compliance with privacy and security controls mandated by these regulations.

Mitigation Strategies

Upgrade aiosmtplib to version 5.1.3 or later immediately. Use: pip install --upgrade aiosmtplib. Review email address validation in your SMTP client code to ensure proper sanitization of inputs.

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