An unintended cleartext issue exists in Go before 1.8.4 and 1.9.x before 1.9.1. RFC 4954 requires that, during SMTP, the PLAIN auth scheme must only be used on network connections secured with TLS. The original implementation of smtp.PlainAuth in Go 1.0 enforced this requirement, and it was documented to do so. In 2013, upstream issue #5184, this was changed so that the server may decide whether PLAIN is acceptable. The result is that if you set up a man-in-the-middle SMTP server that doesn't advertise STARTTLS and does advertise that PLAIN auth is OK, the smtp.PlainAuth implementation sends the username and password.
CVSS Details
- CVSS 3.0 Base Score: 5.9
- CVSS 3.0 Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Alpine Linux | — | alpine-linux-upgrade-go | Oct 25, 2017 | Oct 5, 2017 |
| Amazon Linux Ami 2 | amazon-linux-ami-2-upgrade-golangamazon-linux-ami-2-upgrade-golang-binamazon-linux-ami-2-upgrade-golang-docsamazon-linux-ami-2-upgrade-golang-miscamazon-linux-ami-2-upgrade-golang-srcamazon-linux-ami-2-upgrade-golang-tests | Apr 27, 2020 | Oct 5, 2017 | |
| Amazon_linux | — | amazon-linux-upgrade-golang | Nov 3, 2017 | Oct 5, 2017 |
| Centos_linux | — | centos-upgrade-golangcentos-upgrade-golang-bincentos-upgrade-golang-docscentos-upgrade-golang-misccentos-upgrade-golang-srccentos-upgrade-golang-tests | Aug 28, 2019 | Oct 5, 2017 |
| Gentoo Linux | gentoo-linux-upgrade-dev-lang-go | Oct 30, 2017 | Oct 5, 2017 | |
| Oracle Solaris | oracle-solaris-11-4-upgrade-developer-gcc-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-developer-gcc-9-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-developer-gcc-gcc-c-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-developer-gcc-gcc-c-9-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-developer-gcc-gcc-common-9-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-developer-gcc-gcc-gfortran-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-developer-gcc-gcc-gfortran-9-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-developer-gcc-gcc-go-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-developer-gcc-gcc-go-9-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-developer-gcc-gcc-gobjc-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-developer-gcc-gcc-gobjc-9-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-system-library-gcc-gcc-c-runtime-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-system-library-gcc-gcc-c-runtime-9-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-system-library-gcc-gcc-gfortran-runtime-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-system-library-gcc-gcc-gfortran-runtime-9-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-system-library-gcc-gcc-go-runtime-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-system-library-gcc-gcc-go-runtime-9-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-system-library-gcc-gcc-gobjc-runtime-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-system-library-gcc-gcc-gobjc-runtime-9-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-system-library-gcc-gcc-runtime-9-2-0-11-4-21-0-1-69-0oracle-solaris-11-4-upgrade-system-library-gcc-gcc-runtime-9-9-2-0-11-4-21-0-1-69-0 | Jan 19, 2021 | Oct 5, 2017 | |
| Redhat_linux | — | redhat-upgrade-golangredhat-upgrade-golang-binredhat-upgrade-golang-docsredhat-upgrade-golang-miscredhat-upgrade-golang-srcredhat-upgrade-golang-tests | Apr 11, 2018 | Oct 5, 2017 |
| Suse | — | suse-upgrade-go | Aug 9, 2024 | Oct 5, 2017 |
| Ubuntu | no-fix-ubuntu-package | Jun 26, 2025 | Oct 5, 2017 |
Prioritise with Active Threat Intelligence
With curated Threat Intelligence, you can see which vulnerabilities truly put you at risk, prioritize what matters most, and act before attackers do.
Explore Intelligence Hub