Information Disclosure in craftcms/cms (CVE-2026-56385)
Summary
Vulnerability in craftcms/cms (CVE-2026-56385). Risk of unauthorized operations or information disclosure. Exploitable via previewHtml. Mitigation: upgrade to 4.17.8 or later.
Original description
The description as published by the source.
Craft CMS versions >= 5.0.0-RC1, <= 5.9.13 and >= 4.0.0-RC1, <= 4.17.7 contain an authorization bypass in the assets/preview-file endpoint. The action does not enforce per-asset view authorization before returning preview content, allowing an authenticated low-privileged user to supply a controlled assetId for an asset they are not permitted to view and still receive preview response data (previewHtml), including a private preview image route containing the target private assetId. Fixed in 5.9.14 and 4.17.8.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-56385 has been found in craftcms/cms.
Attackers can target a specific entry point like previewHtml over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.3/10.
What to do: upgrade craftcms/cms to 4.17.8 or later.
If unsure, ask your IT team or search "craftcms/cms CVE-2026-56385" on the vendor's site.
CVE-2026-56385 (craftcms/cms) — CWE-200 / CVSS v3 4.3
Attack vector: remote (network-reachable) / no user interaction
Attack surface: previewHtml / assetId / canView / false
Patched: 4.17.8 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Information disclosure (CWE-200) exists in craftcms/cms. Attackers reach the vulnerable code path via previewHtml.
Check the vendor advisory for the affected versions of craftcms/cms. Attack surface: previewHtml / assetId / canView / false.
Severity: Medium (CVSS 4.3/10). Risk of unauthorized operations or information disclosure.
Update to 4.17.8.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'craftcms/cms' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'craftcms/cms' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
craftcms/cmsを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade craftcms/cms to 4.17.8ステージング環境で 4.17.8 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory vulncheck.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- patch github.com
- web github.com
- web github.com
- web github.com