Is CVE-2026-125756 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-125756 being exploited in the wild.

How severe is CVE-2026-125756?

Medium severity, with a CVSS score of 5.9, published 10 November 2026.

Which products and versions are affected?

Postalsys Postal-Mime before 4.2.1.

Is there a fix for CVE-2026-125756?

Yes: fixed in postal-mime 4.2.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-125756 attacked?

It is attacked over the network.

Am I affected by CVE-2026-125756?

Check whether you run Postalsys Postal-Mime at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-125756: postal-mime address parser domain truncation

CVE-2026-125756 · Severity: medium · CVSS 5.9 · Published 2026-11-10

postal-mime is a JavaScript library for parsing email messages. An attacker can craft email addresses where the parser truncates the domain at whitespace or comments, causing it to report a spoofed sender address while the email passes authentication checks (SPF/DKIM/DMARC) for the attacker's actual domain. This could enable email spoofing attacks where users see a trusted sender address.

Technologies: Postalsys Postal-Mime. Vendors: Postalsys.

Quick answers

Is CVE-2026-125756 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-125756 being exploited in the wild.
How severe is CVE-2026-125756?: Medium severity, with a CVSS score of 5.9, published 10 November 2026.
Which products and versions are affected?: Postalsys Postal-Mime before 4.2.1.
Is there a fix for CVE-2026-125756?: Yes: fixed in postal-mime 4.2.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-125756 attacked?: It is attacked over the network.
Am I affected by CVE-2026-125756?: Check whether you run Postalsys Postal-Mime at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: postal-mime 4.2.1

Technical details

The address parser incorrectly handles RFC 5322 obsolete syntax (CFWS—comments and folding whitespace) around domain dots, truncating the domain prematurely. An attacker can craft addresses like "ceo@victim.example .evil.example" which the parser reads as "ceo@victim.example" (reporting victim as the sender) while passing SPF/DKIM/DMARC alignment checks against the attacker's subdomain. The vulnerability affects parsing of From headers with attacker-controlled input; a network attacker or email sender can exploit this.

Affected products

PostalSys postal-mime before 4.2.1

Timeline

2026-11-10: disclosed

References

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