CVE-2026-125756

Description

postal-mime before 4.2.1 contains a parser differential vulnerability in its address parser that truncates the domain at folding whitespace or comments preceding a dot. Remote attackers can craft From headers that pass SPF/DKIM/DMARC alignment for their own subdomain while PostalMime.parse() reports a spoofed victim sender address.

References

• https://github.com/postalsys/postal-mime/blob/939a220bd518f54d98a088c315d7227e6215cae3/src/address-parser.ts#L265
• https://github.com/postalsys/postal-mime/commit/646725704463839f233472453b7c8306bd1dde21
• https://github.com/postalsys/postal-mime/releases/tag/v4.2.1
• https://github.com/postalsys/postal-mime/security/advisories/GHSA-jh3p-792r-98gm
• https://www.vulncheck.com/advisories/postal-mime-before-4.2.1-sender-spoofing-via-address-parser-domain-truncation