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

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

go-mail is a comprehensive library for sending mails with Go. In versions 0.7.0 and below, 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, there is a possibility of wrong address routing or even ESMTP parameter smuggling. For successful exploitation, it is required that the user's code allows 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 users. This issue is fixed in version 0.7.1

Source published

29 Sep 2025 22:21:02 UTC

Source modified

30 Sep 2025 14:44:35 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 8.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

go-mail is a comprehensive library for sending mails with Go. In versions 0.7.0 and below, 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, there is a possibility of wrong address routing or even ESMTP parameter smuggling. For successful exploitation, it is required that the user's code allows 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 users. This issue is fixed in version 0.7.1

Source published

Sep 29, 2025, 10:21:02 PM (timezone not stated)

Source modified

Sep 30, 2025, 2:44:35 PM (timezone not stated)

Observed here

9 Nov 2026 03:16:01 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 8.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

go-mail is a comprehensive library for sending mails with Go. In versions 0.7.0 and below, 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, there is a possibility of wrong address routing or even ESMTP parameter smuggling. For successful exploitation, it is required that the user's code allows 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 users. This issue is fixed in version 0.7.1

Source published

29 Sep 2025 23:15:31 UTC

Source modified

9 Oct 2026 09:10:00 UTC

Observed here

25 Oct 2026 03:17:27 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 8.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Primary · 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

### 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: `"[email protected]> [email protected]"@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:<[email protected]> [email protected]@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.

Source published

29 Sep 2025 16:28:58 UTC

Source modified

10 Sep 2026 03:50:28 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Publisher rating · HIGH

Insufficient address encoding when passing mail addresses to the SMTP client in github.com/wneessen/go-mail

Source published

5 Nov 2025 18:41:07 UTC

Source modified

4 Feb 2026 02:51:59 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.