aiosmtplib before 5.1.3 ESMTP Parameter Injection via unvalidated addresses (CVE-2026-90467) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-90467

aiosmtplib before 5.1.3 ESMTP Parameter Injection via unvalidated addresses

Answer in brief

CVE-2026-90467 records a Unknown severity vulnerability in aiosmtplib before 5.1.3 ESMTP Parameter Injection via unvalidated addresses. The current sources do not mark it as known exploited. The current feed maps cole/aiosmtplib (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 12, 2026Updated Sep 12, 2026Source checked Sep 12, 2026First seen by HOL Sep 12, 2026Material review Sep 12, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps cole/aiosmtplib (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
cole/aiosmtplibgeneric	>=0 <5.1.3	5.1.3

Recommended response

Check inventory. Check lockfiles and deployed manifests for cole/aiosmtplib.
Review the reported fix. Update cole/aiosmtplib to 5.1.3 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 12, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 12, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 12, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.