Security readout for executives and security teams
Plain-English summary
cypserver is a Node static file server with a directory traversal flaw. If an application exposes it, an attacker may access files outside the intended web directory. Business impact depends on what host files the process can read and whether the service is reachable.
Executive priority
Prioritize exposed services because the issue may turn a simple static file server into a path to sensitive local files. Urgency is lower where cypserver is absent or unreachable.
Technical view
CVE-2017-16191 is CWE-22 in the cypserver node module. The CVE description states all versions are affected and that directory traversal in URLs can give filesystem access. The source bundle provides no CVSS score, no confirmed fixed version, and no named vendor mitigation.
Likely exposure
Exposure is most likely in Node.js applications that depend on cypserver and expose it as a static file server, especially internet-facing or internal shared services.
Exploitation context
The bundle references a public proof-of-concept repository and a Node Security advisory. It does not show CISA KEV listing or any cited evidence of active exploitation.
Researcher notes
Evidence is sparse but consistent: all versions are listed as affected, CWE-22 applies, and public references exist. The source bundle does not provide CVSS, patch details, affected CPEs, or active exploitation confirmation.
Mitigation direction
- Inventory applications and lockfiles for the cypserver dependency.
- Remove or replace cypserver where it is used to serve files.
- Check vendor or advisory guidance for any maintained replacement or fix.
- Restrict service exposure while remediation is planned.
- Limit process filesystem permissions around any affected service.
Validation and detection
- Confirm whether production applications include the cypserver node module.
- Identify any routes or services that expose cypserver file serving.
- Review runtime permissions for files readable by the affected process.
- Check access logs for parent-directory path probing patterns.
- Verify compensating controls prevent access outside intended content roots.
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-22: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. 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 lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2017-16191 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/JacksonGL/NPM-Vuln-PoC/blob/master/directory-traversal/cypserverCVE reference · x_refsource_MISC
- https://nodesecurity.io/advisories/440CVE reference · x_refsource_MISC
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.
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.