Security readout for executives and security teams
Plain-English summary
goshs versions before 2.1.5 allow an unauthenticated remote user to place an uploaded file outside the intended served directory. This could expose or alter data accessible to the goshs process, but the published assessment indicates no availability impact. Version 2.1.5 fixes the flaw.
Executive priority
Prioritize remediation for internet-facing or broadly reachable instances because exploitation needs no credentials or user action. Upgrade promptly through normal emergency or accelerated patching processes. Isolated instances with tightly restricted filesystem permissions may be scheduled by measured exposure, but every version earlier than 2.1.5 should be addressed.
Technical view
The multipart upload handler in httpserver/updown.go split uploaded filenames on forward slashes without rejecting parent-directory components. This path traversal weakness, classified as CWE-22, permits out-of-tree file creation. CVSS 3.1 rates it 6.5: network-accessible, low complexity, no privileges or user interaction, with limited confidentiality and integrity impact.
Likely exposure
Exposure is likely where goshs earlier than 2.1.5 is running and its multipart upload functionality is reachable over a network. Authentication elsewhere, filesystem permissions, process isolation, and network controls may reduce practical impact, but the supplied sources do not document those deployment-specific protections.
Exploitation context
The weakness is remotely reachable and requires no privileges or user interaction according to the CVSS vector. The source bundle provides no evidence of active exploitation, and CVE-2026-66063 is not identified as a CISA KEV entry. Public exploit availability is not established by the supplied sources.
Researcher notes
The affected code is the multipart upload path handling in httpserver/updown.go. The reported flaw concerns insufficient rejection of parent-directory filename components after slash-based processing. The published fix is commit f3ef599e409151d1380866e47de8b1afb0bb54fa and release 2.1.5. The supplied evidence does not establish arbitrary overwrite scope, execution, persistence, or observed attacks.
Mitigation direction
- Upgrade goshs to version 2.1.5 or later.
- Restrict network access to affected goshs instances until upgraded.
- Disable or isolate upload functionality where immediate upgrading is impossible.
- Limit the goshs process filesystem permissions and writable directories.
- Review the vendor advisory before returning affected instances to service.
Validation and detection
- Inventory all goshs deployments and record their installed versions.
- Confirm no running instance uses a version earlier than 2.1.5.
- Identify whether multipart uploads are reachable without authentication.
- Review writable locations outside served trees for unexpected files.
- Verify network controls restrict access to any temporarily unpatched instance.
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-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-2026-66063 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
- 6.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/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.
SSVC decision data
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:L/PR:N/UI:N/S:U/C:L/I:L/A:N3.92.5GitHub_MVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/goshs-labs/goshs/security/advisories/GHSA-wg2q-39h6-66x9CVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/goshs-labs/goshs/commit/f3ef599e409151d1380866e47de8b1afb0bb54faCVE reference, GitHub_M · 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.