CVE-2026-84800 — Craft CMS 5.0.0-RC1 before 5.10.11 File Overwrite via assets/replace-file
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.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.4% (30-day exploitation probability)+4
- Technical severity (high)+6
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Craftcms Cms).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (access control), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.1 | CVSS 4.0 | High | — | — | disclosure@vulncheck.com via NIST National Vulnerability Database |
| 7.1 | CVSS 4.0 | High | — | — | VulnCheck via CVE Program (cve.org) e CISA ADP |
| 7.1 | CVSS 3.1 | High | 2.8 | 4.2 | disclosure@vulncheck.com via NIST National Vulnerability Database |
| 7.1 | CVSS 3.1 | High | — | — | VulnCheck via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L (score shown at the top: disclosure@vulncheck.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Audit administrative actions and access to resources outside each user’s normal pattern.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · craftcms/cms
- SSVC assessment updated
- Record published
- CVSS changed · 7.1
- Source status changed · → Deferred
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-109307 Craft CMS 5.0.0 before 5.10.14 DOM XSS via returnUrl in 2FA Verification 4d
- High CVE-2026-109308 Craft CMS 4.0.0 before 4.18.7 and 5.0.0 before 5.10.14 RCE via actionCacheUpdates Behavior Injection 4d
- High CVE-2026-109305 Craft CMS 5.10.2 before 5.10.14 Twig Sandbox Bypass RCE via has some/has every 4d
- Medium CVE-2026-109304 Craft CMS 4.0.0 before 4.18.7 and 5.0.0 before 5.10.14 Arbitrary File Read via Twig create() DOMDocument 4d
- Medium CVE-2026-109306 Craft CMS 5.0.0 before 5.10.14 Missing Authorization via app/switch-to-licensed-edition 4d
- High CVE-2026-105985 Authenticated RCE via render-components Entry Type overrides 10d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-84800 is "Craft CMS 5.0.0-RC1 before 5.10.11 File Overwrite via assets/replace-file", rated High. It affects Cms (Craftcms); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.1 describes technical severity. EPSS 0.35% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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