Bug 2541880 (CVE-2026-100699)

Summary: CVE-2026-100699 nodemailer: nodemailer: Malformed envelope recipient via crafted email address comments
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: abarbaro, alizardo, dschmidt, ikhan, jchui, jhe, jlanda, kaycoth, kshier, ktsao, lchilton, nboldt, oaljalju, psrna, rbobbitt, rhel-process-autobot, sfeifer, simaishi, stcannon, watson-tool-maintainers, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in nodemailer. The address parser incorrectly processes email addresses containing quoted local parts followed by comments, allowing trailing domain text to be retained in the normalized address. A remote attacker could supply a crafted recipient address to inject malformed domain data into the Simple Mail Transfer Protocol (SMTP) message envelope, potentially leading to unintended email routing or delivery.
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Description OSIDB Bzimport 2026-09-26 13:39:21 UTC 
Nodemailer is a Node.js email-sending library. In versions >= 9.1.0 and < 10.0.9, the address parser (src/addressparser) mishandles addresses whose local-part is a quoted string and that are followed by RFC 5322 comments, allowing trailing comment-separated domain atoms to be retained in the normalized address. For example, the input "user"@example.com(x)evil.com is parsed to the address value 'user evil.com', which contains additional attacker-controlled domain text separated by a literal space. This parsed value is used without further strict recipient validation when the message envelope is built (envelope.to in src/mime-node), so a malformed/ambiguous recipient address can be accepted and placed in the SMTP envelope. Whether this results in delivery to an unintended recipient on real SMTP servers has not been confirmed. The issue is a variant of the RFC 5322 comment parsing problem addressed in GHSA-cc9r-2j5m-2m83, affecting the separate quoted-local-part code path. Version 10.0.9 contains a fix.