How severe is CVE-2026-33158?

No CVSS score has been assigned to CVE-2026-33158 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-33158?

CVE-2026-33158 affects the following packages: craftcms/cms (Packagist), craftcms/cms (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-33158?

Update craftcms/cms to 4.17.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33158 is resolved across your whole dependency graph.

How do I detect CVE-2026-33158 in my Packagist dependencies?

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

How do I mitigate CVE-2026-33158 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-33158 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-33158 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-2026-33158?

CVE-2026-33158 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 30th 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-2026-33158?

CVE-2026-33158 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-2026-33158 published, and has it been updated?

CVE-2026-33158 was published on March 24, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

CVE-2026-33158 — cms

Fix: craftcms/cms@7290d91

CVE-2026-33158 is a CWE-639 vulnerability in craftcms/cms. A fix is available for craftcms/cms — see the affected versions and patch details below.

Craft CMS: Low-privilege users could read private asset contents when editing an asset (IDOR)

Also known asGHSA-3pvf-vxrv-hh9c

Published

Mar 24, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 3, 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-2026-33158.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs30th percentile — riskier than 30% of all scored CVEsHighest risk

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

Real-World Exposure

2 pkgs affected

🐘craftcms/cms🐘craftcms/cms

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

Description

Summary

A low-privileged authenticated user can read private asset content by calling assets/edit-image with an arbitrary assetId that they are not authorized to view.

The endpoint returns image bytes (or a preview redirect) without enforcing a per-asset view authorization check, leading to potential unauthorized disclosure of private files.

Details

Root cause:

A user-controlled object reference (assetId) is used to load and return sensitive content.
The action does not verify whether the current user is authorized to view that asset.
This creates an authenticated IDOR / authorization bypass.

Impact

Craft installations where private/non-public assets exist and low-privileged users can authenticate.

Resources

https://github.com/craftcms/cms/commit/7290d91639e

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`craftcms/cms`	≥ 4.0.0-RC1&&< 4.17.8	4.17.8`composer require craftcms/cms:^4.17.8`
🐘Packagist	`craftcms/cms`	≥ 5.0.0-RC1&&< 5.9.14	5.9.14`composer require craftcms/cms:^5.9.14`

Affected Products

1 product · 8 configurations

Application

craft cmscraftcms

> 5.0.0 && < 5.9.14

2 versions

4.0.05.0.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for craftcms/cms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update craftcms/cms to 4.17.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33158 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Summary A low-privileged authenticated user can read private asset content by calling `assets/edit-image` with an arbitrary `assetId` that they are not authorized to view. The endpoint returns image bytes (or a preview redirect) without enforcing a per-asset view authorization check, leading to potential unauthorized disclosure of private files. ### Details Root cause: - A user-controlled object reference (`assetId`) is used to load and return sensitive content. - The action does not verify whether the current user is authorized to view that asset. - This creates an authenticated

O3 Security · Impact-Aware SCA

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