CVE-2026-84800
HIGHCVE-2026-84800 is a high-severity (CVSS 7.1) CWE-862 vulnerability. O3 Security confirms whether CVE-2026-84800 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Craft CMS versions >= 5.0.0-RC1 and < 5.10.11 contain a missing authorization vulnerability in AssetsController::actionReplaceFile. When a request supplies sourceAssetId and targetFilename…
Description
Craft CMS versions >= 5.0.0-RC1 and < 5.10.11 contain a missing authorization vulnerability in AssetsController::actionReplaceFile. When a request supplies sourceAssetId and targetFilename but omits assetId, the target asset is resolved by folder and filename after the permission checks execute, so the replacePeerFiles permission is never enforced. An authenticated low-privilege author with only the replaceFiles permission on a shared folder can overwrite the content of a peer's asset file (located in the same folder) with attacker-controlled bytes. Fixed in 5.10.11.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-84800 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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.
How O3 protects you
O3 pinpoints whether CVE-2026-84800 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-84800. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-84800 in your dependencies?
O3 detects CVE-2026-84800 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.