Unauthenticated out-of-tree write via dot-dot filename
Published Jul 28, 2026 · Updated Jul 28, 2026
Path traversal in goshs before 2.1.5 allows remote attackers to write a file outside the served tree through a multipart upload. The multipart handler in httpserver/updown.go splits part.FileName() on "/" but accepts "..", so os.Create targets the upload folder's parent and a failed rename leaves the file behind. The default configuration requires no authentication; the published finding demonstrates an out-of-tree write but does not claim a Windows-specific variant.
Summary
What happened
Path traversal in goshs before 2.1.5 allows remote attackers to write a file outside the served tree through a multipart upload. The multipart handler in httpserver/updown.go splits part.FileName() on "/" but accepts "..", so os.Create targets the upload folder's parent and a failed rename leaves the file behind. The default configuration requires no authentication; the published finding demonstrates an out-of-tree write but does not claim a Windows-specific variant.
The record
- CVE
- CVE-2026-66063
- Published
- Jul 28, 2026
- Updated
- Jul 28, 2026
- Vendor
- Patrick Hener
- Product
- goshs
- Classifications
- CWE-22, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 28, 2026CVE publishedPublication date reported by the CVE source.
- Jul 28, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 2.1.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA-wg2q-39h6-66x9 multipart filename proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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