CVE-2026-84800 Craft CMS 5.0.0-RC1 before 5.10.11 File Overwrite via assets/replace-file
An authenticated low-privilege user can overwrite peer asset files in shared folders due to missing permission checks in Craft CMS.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-84800?
CVE-2026-84800 is a high-severity missing authorization vulnerability in craftcms cms, published on 2 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-862
Which versions are affected by CVE-2026-84800?
How do I fix CVE-2026-84800?
No fix has been published for CVE-2026-84800 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-84800 being exploited?
There is no known exploitation of CVE-2026-84800 in the wild and no public exploit code.
Sources
Also known as GHSA-329j-cx85-8r56, GHSA-gr8m-2p6r-xr29.