CVE-2026-40937

HIGH
Published Apr 22, 2026 Modified Apr 24, 2026 CWE-862

Description

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.

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CVSS v3.1 Score

8.3
HIGH
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L

EPSS — Exploit Prediction

0.0007
Probability of exploitation
0.22%
Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-862 Missing Authorization

Affected Products

Vendor Product
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs
rustfs rustfs

References

Frequently Asked Questions

What is CVE-2026-40937? +
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. It has a CVSS v3.1 base score of 8.3 (HIGH).
How severe is CVE-2026-40937? +
CVE-2026-40937 has a CVSS v3.1 score of 8.3 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0007, placing it in the 0th percentile for exploitation probability.
What products are affected by CVE-2026-40937? +
CVE-2026-40937 affects products from rustfs, specifically: rustfs. Check the affected products table above for specific version ranges.
How do I check if I'm vulnerable to CVE-2026-40937? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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