NetSight
IP …
critical9.1

CVE-2025-59937

go-mail has insufficient address encoding when passing mail addresses to the SMTP client

Impact

### Impact Due to incorrect handling of the `mail.Address` values when a sender- or recipient address is passed to the corresponding `MAIL FROM` or `RCPT TO` commands of the SMTP client, this could lead to a possible wrong address routing or even to ESMTP parameter smuggling. #### Vulnerability details Instead of making use of the `String()` method of `mail.Address`, which takes care of proper escaping and quotation of mail address, we used the `Address` value of the `mail.Address` which is the raw value when passing it to our SMTP client. This meant, if a mail address like this was set: `"toni.tester@example.com> ORCPT=admin@admin.com"@example.com` for a sender or recipient, instead of the correctly quoted/escaped address, the SMTP client would get the raw value passed which would translate into something like this being passed to the SMTP server: `RCPT TO:<toni.tester@example.com> ORCPT=admin@admin.com@example.com>`. Since ORCTP is a valid command for the SMTP server, the mail would be routed to the wrong address. Additionally, other SMTP commands could potientially be smuggled in using this method causing unexpected behaviour. #### Exploitation requirements For successful exploitation of this vulnerability it is required that the user's code is allowing for arbitrary mail address input (i. e. through a web form or similar). If only static mail addresses are used (i. e. in a config file) and the mail addresses in use do not consist of quoted local parts, this should not affect your code. ### Patches The vulnerability has been fixed with PR #496 and the fix has been shipped with the go-mail v0.7.1 release. Issue #495 holds the full report and discussion.

Affected packages

EcosystemPackageAffectedFixed in
gogithub.com/wneessen/go-mail< 0.7.10.7.1

Affected products

VendorProductAffected versions
PebcakGo-Mail
before 0.7.1

Weakness classification

CWE-88

References