Security readout for executives and security teams
Plain-English summary
CVE-2018-15473 lets a remote attacker determine whether usernames exist on servers running OpenSSH through 7.7. It does not provide login access by itself, but it can improve password guessing, phishing, and targeted intrusion planning against exposed SSH services.
Executive priority
Treat this as a medium-priority hygiene issue unless SSH is exposed externally. It enables reconnaissance, not direct compromise, but materially helps attackers focus credential attacks on valid accounts.
Technical view
OpenSSH through 7.7 returned or handled invalid authenticating users differently before fully parsing certain authentication packets. The issue is tied to auth2-gss.c, auth2-hostbased.c, and auth2-pubkey.c. CVSS 3.1 rates it 5.9, network-reachable, unauthenticated, high confidentiality impact, no integrity or availability impact.
Likely exposure
Exposure is most likely where SSH is internet-accessible or reachable from untrusted networks and the OpenSSH version is 7.7 or older, including appliances or distributions shipping affected OpenSSH packages.
Exploitation context
The source bundle lists public Exploit-DB entries, so public proof-of-concept material existed. CISA KEV status is false in the bundle, and no provided source proves active exploitation in the wild.
Researcher notes
Do not overstate impact as authentication bypass. The vulnerability is user enumeration caused by premature bailout for invalid users. The bundle does not provide a universal fixed version across all vendors, so validation should be package-advisory based.
Mitigation direction
- Upgrade OpenSSH using the relevant operating system or vendor security advisory.
- Prioritize internet-facing SSH servers and managed appliances with SSH enabled.
- Restrict SSH access to trusted networks, VPNs, or allowlisted administrative IPs.
- Review vendor guidance for NetApp, Siemens, SonicWall, Oracle, Red Hat, Debian, Ubuntu, and Gentoo where applicable.
Validation and detection
- Inventory OpenSSH versions and flag 7.7 or older builds.
- Check OS package changelogs against the listed vendor advisories.
- Identify SSH services exposed to the internet or untrusted networks.
- Review authentication logs for unusual username probing patterns.
- Confirm upgraded hosts no longer report affected OpenSSH package versions.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-362: Exact CWE lookup
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Open ATT&CK lookupCVE-2018-15473 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.9 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N2.23.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.9MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- GLSA-201810-03CVE reference · vendor-advisory
- 45233CVE reference · exploit
- https://bugs.debian.org/906236CVE reference
- 45210CVE reference · exploit
- https://security.netapp.com/advisory/ntap-20181101-0001/CVE reference
- https://github.com/openbsd/src/commit/779974d35b4859c07bc3cb8a12c74b43b0a7d1e0CVE reference
- USN-3809-1CVE reference · vendor-advisory
- [debian-lts-announce] 20180821 [SECURITY] [DLA-1474-1] openssh security updateCVE reference · mailing-list
- DSA-4280CVE reference · vendor-advisory
- 45939CVE reference · exploit
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2018-0011CVE reference
- RHSA-2019:0711CVE reference · vendor-advisory
- RHSA-2019:2143CVE reference · vendor-advisory
- https://www.oracle.com/security-alerts/cpujan2020.htmlCVE reference
- https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdfCVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.