How severe is CVE-2026-105867?

No CVSS score has been assigned to CVE-2026-105867 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-105867?

CVE-2026-105867 affects the following packages: @payloadcms/storage-s3 (npm), @payloadcms/storage-s3 (npm). Ecosystems affected: npm.

How do I fix CVE-2026-105867?

Update @payloadcms/storage-s3 to 3.90.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-105867 is resolved across your whole dependency graph.

How do I detect CVE-2026-105867 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @payloadcms/storage-s3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-105867 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-105867 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-105867 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-105867?

CVE-2026-105867 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 12th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-105867?

CVE-2026-105867 is classified as CWE-639 (CWE-639). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-105867 published, and has it been updated?

CVE-2026-105867 was published on October 6, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

CVE-2026-105867 — @payloadcms/storage-s3

Fix: payloadcms/payload@2df8238

CVE-2026-105867 is a CWE-639 vulnerability in @payloadcms/storage-s3. A fix is available for @payloadcms/storage-s3 — see the affected versions and patch details below.

Payload: Client uploads could overwrite S3 objects

Also known asGHSA-7vg8-29qx-jgj8

Published

Oct 6, 2026

Updated

Oct 21, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-105867.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs12th percentile — riskier than 12% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

📦@payloadcms/storage-s3📦@payloadcms/storage-s3

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

Description

Impact

An authenticated user could overwrite an existing S3 object belonging to another upload collection, bypassing that collection’s access controls and prior file validation.

You are affected if ALL of these are true:

Client uploads are enabled for multiple collections that share an S3 bucket.
useCompositePrefixes is not configured or is set to false.

Patches

Users should upgrade Payload packages to >= 3.90.0 or >= 4.0.0-canary.34.

Workarounds

Disable client uploads until you can upgrade.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@payloadcms/storage-s3`	all versions	3.90.0`npm install @payloadcms/storage-s3@3.90.0`
📦npm	`@payloadcms/storage-s3`	≥ 4.0.0-canary.0&&< 4.0.0-canary.34	4.0.0-canary.34`npm install @payloadcms/storage-s3@4.0.0-canary.34`

Affected Products

1 product · 35 configurations

Application

payloadpayloadcms

< 3.90.0

1 version

4.0.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @payloadcms/storage-s3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @payloadcms/storage-s3 to 3.90.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-105867 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### Impact An authenticated user could overwrite an existing S3 object belonging to another upload collection, bypassing that collection’s access controls and prior file validation. You are affected if ALL of these are true: - Client uploads are enabled for multiple collections that share an S3 bucket. - useCompositePrefixes is not configured or is set to `false`. ### Patches Users should upgrade Payload packages to `>= 3.90.0` or `>= 4.0.0-canary.34`. ### Workarounds Disable client uploads until you can upgrade.

O3 Security · Impact-Aware SCA

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