Critical Access control exploit reference

CVE-2026-40189 — goshs has a file-based ACL authorization bypass in goshs state-changing routes

goshs is a SimpleHTTPServer written in Go. Prior to 2.0.0-beta.4, goshs enforces the documented per-folder .goshs ACL/basic-auth mechanism for directory listings and file reads, but it does not enforce the same authorization checks for state-changing routes. An unauthenticated attacker can upload files with PUT, upload files with multipart POST /upload, create directories with ?mkdir, and delete files with ?delete inside a .goshs-protected directory. By deleting the .goshs file itself, the attacker can remove the folder's auth policy and then access previously protected content without credentials. This results in a critical authorization bypass affecting confidentiality, integrity, and availability. This vulnerability is fixed in 2.0.0-beta.4.

Published Apr 10, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Moderate

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.7% (30-day exploitation probability)+8
Technical severity (critical)+10
CISA SSVC: exploitation "poc"+5
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.66%

ahead of 50% of scored CVEs · Oct 14, 2026

Affects

Goshs

CVSS base

9.8

Critical · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — github.com (NIST National Vulnerability Database)
Documented mitigation — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Goshs Goshs, Patrickhener Goshs).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes matching the vulnerability class (access control), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Goshs	Goshs	< 2.0.0version 2.0.0-beta1version 2.0.0-beta2version 2.0.0-beta3	Vulnerable	NIST National Vulnerability Database
Patrickhener	Goshs	version < 2.0.0-beta.4	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.3	CVSS 4.0	Critical	—	—	security-advisories@github.com via NIST National Vulnerability Database
9.3	CVSS 4.0	Critical	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP
9.8	CVSS 3.1	Critical	3.9	5.9	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-862 · Missing Authorization

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.66%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Audit administrative actions and access to resources outside each user’s normal pattern.

web/proxy/WAF logsnetwork IDS/IPSauthentication logsapplication logs

Timeline

What happened to this CVE, newest first.

2026
Affected products added · patrickhener/goshs
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 9.8
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Apr 10, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

3 on the record

github.com/patrickhener/goshs/security/advisories/GHSA-wvhv-qcqf-f3cx
Exploit, Mitigation, Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
github.com/patrickhener/goshs/commit/f212c4f4a126556bab008f79758e21a839ef2c0f
Patch, x_refsource_MISC, NIST National Vulnerability Database
github.com/patrickhener/goshs/releases/tag/v2.0.0-beta.4
Product, Release Notes, x_refsource_MISC, NIST National Vulnerability Database

Elsewhere on this site

Goshs
every CVE for this vendor

Access control
same class

CWE-862
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-42091 goshs has Cross-Origin Arbitrary File Write via Missing CSRF on PUT and Wildcard CORS May 4, 2026
Critical CVE-2026-40884 goshs: Empty-username SFTP password authentication bypass in goshs Apr 21, 2026
High CVE-2026-40885 goshs: Public collaborator feed leaks .goshs ACL credentials and enables unauthorized access Apr 21, 2026
Critical CVE-2026-40903 Goshs - ArtiPACKED Vulnerability – GitHub Actions Credential Persistence Apr 21, 2026
High CVE-2026-40876 SFTP root escape via prefix-based path validation in goshs Apr 21, 2026
High CVE-2026-40883 goshs: CSRF in state-changing GET routes enables authenticated file deletion and directory creation Apr 21, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-40189 is "goshs has a file-based ACL authorization bypass in goshs state-changing routes", rated Critical. It affects Goshs (Goshs); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 0.66% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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