Bug 2552965 (CVE-2026-110871)

Summary: CVE-2026-110871 nodemailer: nodemailer: Denial of Service via inefficient header parsing
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. A remote attacker can trigger a Denial of Service (DoS) by submitting emails containing excessively long headers or large recipient lists that fold into numerous continuation lines. Inefficient header parsing in the message parser component leads to excessive CPU resource consumption, which blocks the application event loop during email signing.
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Description OSIDB Bzimport 2026-10-14 23:01:53 UTC 
Nodemailer from 3.0.0 before 10.0.10 contains a denial of service vulnerability in MessageParser.parseHeaders that allows users to exhaust CPU through quadratic header unfolding. Attackers can supply large recipient lists or long headers that fold into tens of thousands of continuation lines, blocking the Node.js event loop during DKIM signing.