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CVE-2017-15042

22
FAUCET Score

CVE-2017-15042 describes an unintended cleartext issue in Go versions before 1.8.4 and 1.9.1, specifically within the smtp.PlainAuth implementation. This vulnerability allows a man-in-the-middle attacker to intercept usernames and passwords if a malicious SMTP server advertises PLAIN authentication without STARTTLS. Rated Medium severity (CVSS 5.9), it requires high attack complexity and can lead to full confidentiality compromise. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.8.3CPE matchmatch criteria
cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*
1.9CPE matchmatch criteria
cpe:2.3:a:golang:go:1.9:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

5.9MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.10%
Probability of exploitation in next 30 days
EPSS Percentile
62.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0111 is in the 24th percentile among its peer group of 19,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (7)

github_advisorypatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Developer ToolsFixed in: go-toolset-7-0:1.8-10.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Developer ToolsFixed in: go-toolset-7-golang-0:1.8.5-1.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: golang-0:1.9.4-1.el7
View patch
redhatno patchvia redhat_api
Product: Red Hat OpenShift Enterprise 3Fixed in: golang
redhatend of lifevia redhat_api
Product: Red Hat OpenStack Platform 8 (Liberty) Operational ToolsFixed in: golang
redhatend of lifevia redhat_api
Product: Red Hat OpenStack Platform 9 (Mitaka) Operational ToolsFixed in: golang

Vendor Advisories (2)

microsoft2017-Oct/CVE-2017-15042Moderate

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.

Oct 10, 2017
redhatCVE-2017-15042Moderate

golang: smtp.PlainAuth susceptible to man-in-the-middle password harvesting

Oct 4, 2017

References

access.redhat.com / errata/RHSA-2017:3463
access.redhat.com / errata/RHSA-2018:0878
github.com / golang/go/issues/22134
Issue TrackingPatchVendor Advisory
golang.org / cl/68023
Issue TrackingPatchVendor Advisory
golang.org / cl/68210
Vendor Advisory
groups.google.com / d/msg/golang-dev/RinSE3EiJBI/kYL7zb07AgAJ
Mailing ListVendor Advisory
security.gentoo.org / glsa/201710-23
Third Party Advisory
securityfocus.com / bid/101197
Third Party AdvisoryVDB Entry