CVE-2026-53533

aiosmtplib is an asynchronous SMTP client for use with asyncio. Prior to 5.1.1, SMTP.mail(), SMTP.rcpt(), SMTP.vrfy(), and SMTP.expn() send caller-supplied addresses without rejecting embedded CR or LF bytes. Data after the line break is framed as additional standalone SMTP command lines, allowing an attacker who influences an envelope sender or recipient to inject commands such as MAIL FROM, RCPT TO, RSET, DATA, or AUTH. SMTP.sendmail() and SMTP.send() without a Message object pass addresses through the affected methods, while SMTP.send_message() is not affected. Successful injection can desynchronize the command-response pipeline, hang the SMTP instance, or send an arbitrary message without requiring attacker control of the SMTP server. This issue is fixed in version 5.1.1.

CVSS

No CVSS.

References

Link	Resource
https://github.com/cole/aiosmtplib/commit/8eaf6efc9a8f59e2e09d3ef11246a058c46bd3ba
https://github.com/cole/aiosmtplib/releases/tag/v5.1.1
https://github.com/cole/aiosmtplib/security/advisories/GHSA-v3q9-hj7j-63hq

Configurations

No configuration.

History

No history.

Information

Published : 2026-08-18 18:18

Updated : 2026-08-19 19:17

NVD link : CVE-2026-53533

Mitre link : CVE-2026-53533

CVE.ORG link : CVE-2026-53533

JSON object : View

Products Affected

No product.

CWE

CWE-77

Improper Neutralization of Special Elements used in a Command ('Command Injection')

CWE-93

Improper Neutralization of CRLF Sequences ('CRLF Injection')

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