CVE-2018-16886

etcd versions 3.2.x before 3.2.26 and 3.3.x before 3.3.11 are vulnerable to an improper authentication issue when role-based access control (RBAC) is used and client-cert-auth is enabled. If an etcd client server TLS certificate contains a Common Name (CN) which matches a valid RBAC username, a remote attacker may authenticate as that user with any valid (trusted) client certificate in a REST API request to the gRPC-gateway.

Published: 2019-01-14 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-16886 is rated High Risk (67.2/100): CVSS High severity, with medium exploitation likelihood (EPSS 4.03%). EPSS rose +3.54% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-16886

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.49% 4.03% +3.54%
2 2026-04-29 0.78% 0.49% -0.30%
3 2025-11-24 — 0.78% —

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-16886

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.1 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 5.9 [email protected]
6.8 3.0 MEDIUM
CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 5.2 [email protected]
6.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 6.4 [email protected]

Weakness enumeration for CVE-2018-16886

GitHub Security Advisory for CVE-2018-16886

GHSA-h6xx-pmxh-3wgp · Severity: high · Ecosystem: go — go.etcd.io/etcd Authentication Bypass

OS Trackers for CVE-2018-16886

vendor priority summary link
debian not yet assigned CVE-2018-16886 not yet assigned priority: Debian including 1 source packages (etcd), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2018-16886
redhat medium — https://access.redhat.com/security/cve/CVE-2018-16886
suse medium CVE-2018-16886 severity moderate: SUSE including 9 source package names (2.4.6-6.1:etcd-3.5.12-150000.7.6.1, etcd, …), 14 product×package rows across 8 product lines (Container containers/milvus, Magnum Orchestration 7, … (8 product lines)): Fixed 12, Known Not Affected 2. https://www.suse.com/security/cve/CVE-2018-16886/
ubuntu medium CVE-2018-16886 medium priority: Ubuntu including 1 source packages (etcd), 19 status rows across 19 suites (bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 14, ignored 2, DNE 1, needed 1, released 1. https://ubuntu.com/security/CVE-2018-16886

Affected software / configurations for CVE-2018-16886

Vendor Product Version Raw CPE
etcd etcd >= 3.2.0, < 3.2.26 cpe:2.3:a:etcd:etcd:*:*:*:*:*:*:*:*
etcd etcd >= 3.3.0, < 3.3.11 cpe:2.3:a:etcd:etcd:*:*:*:*:*:*:*:*
redhat enterprise_linux_desktop 7.0 cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_server 7.0 cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_workstation 7.0 cpe:2.3:o:redhat:enterprise_linux_workstation:7.0:*:*:*:*:*:*:*
fedoraproject fedora 30 cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*

References for CVE-2018-16886

URL Tags
http://www.securityfocus.com/bid/106540 Third Party Advisory VDB Entry
https://access.redhat.com/errata/RHSA-2019:0237 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:1352 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-16886 Issue Tracking Patch Third Party Advisory
https://github.com/etcd-io/etcd/blob/1eee465a43720d713bb69f7b7f5e120135fdb1ac/CHANGELOG-3.2.md#security-authentication Release Notes
https://github.com/etcd-io/etcd/blob/1eee465a43720d713bb69f7b7f5e120135fdb1ac/CHANGELOG-3.3.md#security-authentication Release Notes
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JX7QTIT465BQGRGNCE74RATRQLKT2QE4/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UPGYHMSKDPW5GAMI7BEP3XQRVRLLBJKS/
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