Security readout for executives and security teams
Plain-English summary
This flaw affects the OpenSSH scp client. A malicious or compromised SSH server could abuse unusual filenames to change permissions on the client’s target directory. It is not a remote server takeover, but it can weaken client-side file protections when users or automation pull files with scp.
Executive priority
Treat as a moderate client-side integrity issue. It deserves routine but prompt patching, especially on admin and automation systems. Escalate only if business processes rely on scp downloads from untrusted or customer-controlled servers.
Technical view
CVE-2018-20685 is an OpenSSH 7.9 scp.c authorization/access-control flaw involving a filename of . or an empty filename. The documented impact is client-side target-directory permission modification. The CVSS 3.1 score is 5.3 with network attack vector, high complexity, and required user interaction.
Likely exposure
Exposure is mainly on systems using vulnerable OpenSSH scp clients, especially administrator workstations, build hosts, and scripts that download files from less-trusted SSH servers. The source bundle does not provide a complete affected-product matrix beyond OpenSSH 7.9 and vendor advisories.
Exploitation context
The source bundle does not show KEV listing or active exploitation. Abuse requires the client to connect with scp to a malicious or compromised SSH server. The practical risk is higher where users or automation retrieve files from third-party, shared, or poorly controlled servers.
Researcher notes
Evidence points to a narrow scp client flaw, categorized as CWE-863. The upstream OpenSSH and OpenBSD references provide the code-level fix context. Do not infer broader SSH daemon compromise; the described impact is target-directory permission modification on the client side.
Mitigation direction
- Apply OpenSSH updates from the operating-system or appliance vendor advisory.
- Prioritize clients that pull files from external or untrusted SSH servers.
- Avoid legacy scp downloads from untrusted servers until patched.
- Check NetApp, Oracle, Siemens, and distribution advisories where relevant.
- Use vendor guidance rather than assuming one universal fixed version.
Validation and detection
- Inventory systems using OpenSSH scp clients and record package versions.
- Compare installed packages against Debian, Ubuntu, Gentoo, Red Hat, and vendor advisories.
- Review automation that pulls files using scp from remote servers.
- Confirm patched clients no longer match vulnerable vendor package ranges.
- Inspect sensitive download directories for unexpected permission weakening.
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-863: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2018-20685 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
- 5.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/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:R/S:U/C:N/I:H/A:N1.63.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.3MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- DSA-4387CVE reference · vendor-advisory
- USN-3885-1CVE reference · vendor-advisory
- https://github.com/openssh/openssh-portable/commit/6010c0303a422a9c5fa8860c061bf7105eb7f8b2CVE reference
- https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/scp.c.diff?r1=1.197&r2=1.198&f=hCVE reference
- https://security.netapp.com/advisory/ntap-20190215-0001/CVE reference
- https://sintonen.fi/advisories/scp-client-multiple-vulnerabilities.txtCVE reference
- GLSA-201903-16CVE reference · vendor-advisory
- [debian-lts-announce] 20190325 [SECURITY] [DLA 1728-1] openssh security updateCVE reference · mailing-list
- https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.htmlCVE reference
- https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.htmlCVE reference
- RHSA-2019:3702CVE reference · vendor-advisory
- GLSA-202007-53CVE reference · vendor-advisory
- 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.
Incorrect Authorization
Incorrect Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.