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CVE-2026-90467

4.0 · MEDIUM

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.

Published Sep 12, 2026CWE-88EPSS 0.39%

Overview

CVE-2026-90467 is a medium-severity vulnerability. It was published on September 12, 2026 and has a CVSS 3.1 base score of 4.0 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.0, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/cole/aiosmtplibGitHubgithub.com/cole/aiosmtplib/blob/v5.1.2/src/aiosmtplib/email.pyGitHubgithub.com/cole/aiosmtplib/commit/2e1b210714974ccc9efd0d09a8f846cb9aeaaec2GitHubgithub.com/cole/aiosmtplib/releases/tag/v5.1.3Refwww.vulncheck.com/advisories/aiosmtplib-before-5.1.3-esmtp-parameter-injection-via-unvalidated-addresses

How CyberStrike helps

Frequently asked questions

What is CVE-2026-90467?

CVE-2026-90467 is a medium-severity vulnerability. It was published on September 12, 2026 and has a CVSS 3.1 base score of 4.0 (MEDIUM).

How severe is CVE-2026-90467?

This vulnerability has a CVSS 3.1 base score of 4.0, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-90467?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-90467?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-90467 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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