High Access control

CVE-2026-40937 — RustFS missing admin authorization on notification target endpoints, which allows unauthenticated configuration of event webhooks

RustFS is a distributed object storage system built in Rust. Prior to 1.0.0-alpha.94, all four notification target admin API endpoints in `rustfs/src/admin/handlers/event.rs` use a `check_permissions` helper that validates authentication only (access key + session token), without performing any admin-action authorization via `validate_admin_request`. Every other admin handler in the codebase correctly calls `validate_admin_request` with a specific `AdminAction`. This is the only admin handler file that skips authorization. A non-admin user can overwrite a shared admin-defined notification target by name, causing subsequent bucket events to be delivered to an attacker-controlled endpoint. This enables cross-user event interception and audit evasion. 1.0.0-alpha.94 contains a patch.

Published Apr 22, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Low

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 0.5% (30-day exploitation probability)+6
Technical severity (high)+6

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

0.49%

ahead of 40% of scored CVEs · Oct 14, 2026

Affects

Rustfs

CVSS base

8.3

High · 2 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

None

none · proof-of-concept · active

Automatable

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 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 (Rustfs Rustfs).
Apply the documented mitigations until a definitive fix is available.
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
Rustfs	Rustfs	version 1.0.0-alpha63version 1.0.0-alpha73version 1.0.0-alpha72version 1.0.0-alpha71version 1.0.0-alpha70version 1.0.0-alpha7version 1.0.0-alpha69version 1.0.0-alpha68 and 85 more version 1.0.0-alpha67version 1.0.0-alpha66version 1.0.0-alpha65version 1.0.0-alpha64version 1.0.0-alpha74version 1.0.0-alpha62version 1.0.0-alpha61version 1.0.0-alpha60version 1.0.0-alpha6version 1.0.0-alpha59version 1.0.0-alpha58version 1.0.0-alpha57version 1.0.0-alpha56version 1.0.0-alpha55version 1.0.0-alpha54version 1.0.0-alpha53version 1.0.0-alpha84version 1.0.0-alpha93version 1.0.0-alpha92version 1.0.0-alpha91version 1.0.0-alpha90version 1.0.0-alpha9version 1.0.0-alpha89version 1.0.0-alpha88version 1.0.0-alpha87version 1.0.0-alpha86version 1.0.0-alpha85version 1.0.0-alpha52version 1.0.0-alpha83version 1.0.0-alpha82version 1.0.0-alpha81version 1.0.0-alpha80version 1.0.0-alpha8version 1.0.0-alpha79version 1.0.0-alpha78version 1.0.0-alpha77version 1.0.0-alpha76version 1.0.0-alpha75version 1.0.0-alpha20version 1.0.0-alpha30version 1.0.0-alpha3version 1.0.0-alpha29version 1.0.0-alpha28version 1.0.0-alpha27version 1.0.0-alpha26version 1.0.0-alpha25version 1.0.0-alpha24version 1.0.0-alpha23version 1.0.0-alpha22version 1.0.0-alpha21version 1.0.0-alpha31version 1.0.0-alpha2version 1.0.0-alpha19version 1.0.0-alpha18version 1.0.0-alpha17version 1.0.0-alpha16version 1.0.0-alpha15version 1.0.0-alpha14version 1.0.0-alpha13version 1.0.0-alpha12version 1.0.0-alpha11version 1.0.0-alpha10version 1.0.0-alpha41version 1.0.0-alpha51version 1.0.0-alpha50version 1.0.0-alpha5version 1.0.0-alpha49version 1.0.0-alpha48version 1.0.0-alpha47version 1.0.0-alpha46version 1.0.0-alpha45version 1.0.0-alpha44version 1.0.0-alpha43version 1.0.0-alpha42version 1.0.0-alpha1version 1.0.0-alpha40version 1.0.0-alpha4version 1.0.0-alpha39version 1.0.0-alpha38version 1.0.0-alpha37version 1.0.0-alpha36version 1.0.0-alpha35version 1.0.0-alpha34version 1.0.0-alpha33version 1.0.0-alpha32	Vulnerable	NIST National Vulnerability Database
Rustfs	Rustfs	version < 1.0.0-alpha.94	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

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

Low

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
8.3	CVSS 3.1	High	2.8	5.5	security-advisories@github.com via NIST National Vulnerability Database
8.3	CVSS 3.1	High	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L (score shown at the top: security-advisories@github.com)

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 0.49%

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 · rustfs/rustfs
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 · 8.3
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 22, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

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

References

2 on the record

github.com/rustfs/rustfs/security/advisories/GHSA-pfcq-4gjr-6gjm
Mitigation, Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
github.com/rustfs/rustfs/releases/tag/1.0.0-alpha.94
Product, Release Notes, x_refsource_MISC, NIST National Vulnerability Database

Elsewhere on this site

Rustfs
every CVE for this vendor

Access control
same class

CWE-862
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-55838 RustFS: Missing admin authorization on /rustfs/admin/v3/metrics allows any authenticated user to read server metrics Jun 26, 2026
High CVE-2026-55188 RustFS: ListRemoteTargetHandler authorization bypass leaks replication target credentials Jun 26, 2026
High CVE-2026-55189 RustFS: FTP frontend skips IAM authorization on object reads Jun 26, 2026
High CVE-2026-49991 RustFS Snowball Auto-Extract: Path Traversal allows cross-bucket object injection Jun 26, 2026
Critical CVE-2026-45043 RustFS: ImportIam Allows Creation of Backdoor Service Accounts Under Any Parent Including Root May 29, 2026
Medium CVE-2026-47136 RustFS: Unauthenticated RustFS console license endpoint exposes license metadata May 28, 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-2026-40937 is "RustFS missing admin authorization on notification target endpoints, which allows unauthenticated configuration of event webhooks", rated High. It affects Rustfs (Rustfs); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.3 describes technical severity. EPSS 0.49% 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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