CVE-2026-40876Public exploitNetwork attack vector

SFTP jail escape via prefix-only path validation

Published Apr 21, 2026 · Updated Apr 21, 2026

Path traversal in goshs before 2.0.0-beta.6 allows remote authenticated users to read and write files outside the configured SFTP root. sanitizePath in sftpserver/helper.go applies strings.HasPrefix to the cleaned client path and root without enforcing a directory boundary, so sibling paths sharing the root's byte prefix pass validation. Access requires valid SFTP credentials and knowledge of a matching sibling path; successful requests can disclose, create, overwrite, rename, or delete files permitted to the server process.

CVSS severity8.7
High
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in goshs before 2.0.0-beta.6 allows remote authenticated users to read and write files outside the configured SFTP root. sanitizePath in sftpserver/helper.go applies strings.HasPrefix to the cleaned client path and root without enforcing a directory boundary, so sibling paths sharing the root's byte prefix pass validation. Access requires valid SFTP credentials and knowledge of a matching sibling path; successful requests can disclose, create, overwrite, rename, or delete files permitted to the server process.

The record

CVE
CVE-2026-40876
Published
Apr 21, 2026
Updated
Apr 21, 2026
Vendor
Patrick Hener
Product
goshs
Classifications
CWE-22, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 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.

  1. Affected versionversion=< 2.0.0-beta.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Patrick Hener · goshsversion=< 2.0.0-beta.6

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.7GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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