# CVE-2026-72778: Craft CMS 5.0.0-RC1 before 5.10.6 Authenticated RCE via condition.config

> Authenticated attackers can execute arbitrary code via unsafe JSON decoding in Craft CMS control panel condition handling.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Aug 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-265m-7826-wjqm

## What is CVE-2026-72778?

CVE-2026-72778 is a high-severity code injection vulnerability in craftcms cms, published on 11 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Craft CMS versions from 4.0.0-RC1 before 4.18.2 and from 5.0.0-RC1 before 5.10.6 contain an authenticated remote code execution vulnerability in the control panel element-search condition handling. Craft cleanses the outer request-controlled condition array via Component::cleanseConfig(), but Conditions::createCondition() later decodes and merges the JSON string in condition.config without re-running cleanseConfig() on the decoded configuration. Because condition.config is a JSON string during the first cleanse, Yii special config keys such as 'as ...' and 'on ...' can be hidden inside it and, after JSON decoding, are interpreted by Yii as behavior/event configuration during FieldLayout object creation. An attacker with an authenticated control panel session (and a valid CSRF token) can exploit this to execute operating system commands as the PHP/web user.

Weakness: CWE-915 (Improperly Controlled Modification of Dynamically-Determined Object Attributes)

## Which versions are affected by CVE-2026-72778?

4 open source packages ship an affected version, including craftcms/cms.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `craftcms/cms` | Packagist | From 4.0.0-RC1 | 4.18.2 |
| `craftcms/cms` | Packagist | From 4.0.0-RC1 | 4.18.2 |
| `craftcms/cms` | Packagist | From 5.0.0-RC1 | 5.10.6 |
| `craftcms/cms` | Packagist | From 5.0.0-RC1 | 5.10.6 |

## How do I fix CVE-2026-72778?

Upgrade craftcms/cms to a fixed version for your release line: 4.18.2 or 5.10.6.

## Is CVE-2026-72778 being exploited?

There is no known exploitation of CVE-2026-72778 in the wild and no public exploit code.

Public exploit code:

- Craft CMS CVE-2026-72778 condition.config RCE PoC (github_poc): https://github.com/TRX-0/CVE-2026-72778-craftcms-rce

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72778 and fix it if it is affected.

What it is: CVE-2026-72778 is a high-severity code injection vulnerability in craftcms cms, published on 11 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72778 in the wild and no public exploit code.

Affected packages and fixed versions:
- craftcms/cms (Packagist): affected from 4.0.0-RC1; fixed in 4.18.2
- craftcms/cms (Packagist): affected from 4.0.0-RC1; fixed in 4.18.2
- craftcms/cms (Packagist): affected from 5.0.0-RC1; fixed in 5.10.6
- craftcms/cms (Packagist): affected from 5.0.0-RC1; fixed in 5.10.6

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-72778/ (Markdown: https://insights.sbomify.com/CVE-2026-72778/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72778
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72778
- OSV: https://osv.dev/vulnerability/CVE-2026-72778

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72778/
Summaries are generated and may contain mistakes; the official description above is the record.