How severe is CVE-2026-42091?

CVE-2026-42091 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2026-42091 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42091?

CVE-2026-42091 affects Goshs. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-42091?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-42091 have an EU (EUVD) identifier?

Yes. CVE-2026-42091 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27067.

When was CVE-2026-42091 published?

CVE-2026-42091 was published on 2026-05-04 and last updated on 2026-06-17.

CVE-2026-42091

CVE-2026-42091 is a medium-severity vulnerability in Goshs with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-352.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (6th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-27067
Weakness: CWE-352
Affected product: Goshs
Published: 2026-05-04
Last modified: 2026-06-17

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.

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 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2026-42091 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42091?: CVE-2026-42091 affects Goshs. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42091?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-42091 have an EU (EUVD) identifier?: Yes. CVE-2026-42091 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27067.
When was CVE-2026-42091 published?: CVE-2026-42091 was published on 2026-05-04 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:goshs:goshs:*:*:*:*:*:go:*:*

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