---
id: "CVE-2026-125756"
page: "https://infrastack.ai/live/CVE-2026-125756"
kind: "vulnerability"
aliases: ["CVE-2026-125756"]
title: "postal-mime: address parser truncates domain, letting spoofed sender pass checks"
severity: "high"
cvss: 8.2
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["email-parsing", "node", "package", "postal-mime"]
not_affected_if: ["sender-not-trusted", "version-4.2.1-or-later"]
published_at: "2026-11-10T16:17:22+00:00"
first_seen_at: "2026-11-10T16:22:35+00:00"
updated_at: "2026-11-10T16:23:24+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125756", "first_seen_at": "2026-11-10T16:22:35+00:00"}]
exploit_sources: []
---

# postal-mime: address parser truncates domain, letting spoofed sender pass checks

Link for people: https://infrastack.ai/live/CVE-2026-125756 (this .md is for agents)

postal-mime before 4.2.1 truncates the sender domain in its address parser when folding whitespace or comments precede a dot. An attacker can craft a From header that passes SPF, DKIM and DMARC for their own subdomain while the parsed sender shows a spoofed victim address.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed postal-mime version in your lockfile or with `npm ls postal-mime`
- Look for code that calls `PostalMime.parse()` and trusts the parsed `from` address for authorization or display decisions

## Fix

- postal-mime: upgrade to `4.2.1` or later

## Timeline

- 2026-11-10T16:22:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125756

## Documents

- [advisory] Vendor advisory: github.com https://github.com/postalsys/postal-mime/security/advisories/GHSA-jh3p-792r-98gm
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/postal-mime-before-4.2.1-sender-spoofing-via-address-parser-domain-truncation
- [fix] Patch: github.com https://github.com/postalsys/postal-mime/commit/646725704463839f233472453b7c8306bd1dde21
- [fix] Release notes: github.com https://github.com/postalsys/postal-mime/releases/tag/v4.2.1

## From the sources

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.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_