CVE-2026-42091: goshs is a SimpleHTTPServer written in Go. Prior to version 2.0.2, the PUT upload handler (httpserver/updown.go) lacks the CSRF token validation that ...

Description

goshs is a SimpleHTTPServer written in Go. Prior to version 2.0.2, the PUT upload handler (httpserver/updown.go) lacks the CSRF token validation that was added to the POST upload handler during the CVE-2026-40883 fix. Combined with the unconditional Access-Control-Allow-Origin: * on the OPTIONS preflight handler (httpserver/server.go), any website can write arbitrary files to a goshs instance through the victim's browser — bypassing network isolation (e.g. localhost, internal network). This issue has been patched in version 2.0.2.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS Probability

0.17%

6.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-352

Affected Software

Vendor	Product	Versions
Goshs	Goshs	< 2.0.2

References

https://github.com/patrickhener/goshs/commit/0e715b94e10c3d1aa552276000f15f104dee2f32Patch
https://github.com/patrickhener/goshs/releases/tag/v2.0.2Product, Release Notes
https://github.com/patrickhener/goshs/security/advisories/GHSA-rhf7-wvw3-vjvmExploit, Vendor Advisory
https://github.com/patrickhener/goshs/security/advisories/GHSA-rhf7-wvw3-vjvmExploit, Vendor Advisory

Timeline

Published: May 4, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-42091?

goshs is a SimpleHTTPServer written in Go. Prior to version 2.0.2, the PUT upload handler (httpserver/updown.go) lacks the CSRF token validation that was added to the POST upload handler during the CVE-2026-40883 fix. Combined with the unconditional Access-Control-Allow-Origin: * on the OPTIONS preflight handler (httpserver/server.go), any website can write arbitrary files to a goshs instance through the victim's browser — bypassing network isolation (e.g. localhost, internal network). This issue has been patched in version 2.0.2.

How severe is CVE-2026-42091?

CVE-2026-42091 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.

How do I fix CVE-2026-42091?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

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