vulnerability / NVI-00002249 / Revision 1
Craft CMS vulnerable to potential authenticated Remote Code Execution via malicious attached Behavior
OSV carries this publisher advisory for craftcms/cms, craftcms/cms. This is an aggregated source copy; consult the original publisher and compare update dates.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
craftcms/cms
source listedECOSYSTEM: introduced 5.0.0-RC1; fixed 5.8.21
Note that attackers must have administrator access to the Craft Control Panel for this to work. Users should update to the patched versions (5.8.21 and 4.16.17) to mitigate the issue. Resources: https://github.com/craftcms/cms/commit/6e608a1a5bfb36943f94f584b7548ca542a86fef https://github.com/craftcms/cms/commit/27f55886098b56c00ddc53b69239c9c9192252c7 https://github.com/craftcms/cms/commit/ec43c497edde0b2bf2e39a119cded2e55f9fe593 https://github.com/craftcms/cms/blob/5.x/CHANGELOG.md#5821---2025-12-04 ### Summary This was reported as a vulnerability in Yii framework on August 7th (https://github.com/yiisoft/yii2/security/advisories/GHSA-gcmh-9pjj-7fp4). The Yii framework team denies responsibility for this (placing the onus on application developers) and hence has not (and seemingly will not) provide a fix at the framework level. Hence, I am reporting this to Craft as I found it to affect the latest (`5.6.0`) version of Craft CMS. Leveraging a legitimate but maliciously crafted Yii `Behavior` class, it’s possible to trigger Remote Code Execution (RCE) via Reflection when the tainted `Behavior` is attached to a Yii `Component`, and an event is also fired on the tainted `Com
craftcms/cms
source listedECOSYSTEM: introduced 4.0.0-RC1; fixed 4.16.17
Note that attackers must have administrator access to the Craft Control Panel for this to work. Users should update to the patched versions (5.8.21 and 4.16.17) to mitigate the issue. Resources: https://github.com/craftcms/cms/commit/6e608a1a5bfb36943f94f584b7548ca542a86fef https://github.com/craftcms/cms/commit/27f55886098b56c00ddc53b69239c9c9192252c7 https://github.com/craftcms/cms/commit/ec43c497edde0b2bf2e39a119cded2e55f9fe593 https://github.com/craftcms/cms/blob/5.x/CHANGELOG.md#5821---2025-12-04 ### Summary This was reported as a vulnerability in Yii framework on August 7th (https://github.com/yiisoft/yii2/security/advisories/GHSA-gcmh-9pjj-7fp4). The Yii framework team denies responsibility for this (placing the onus on application developers) and hence has not (and seemingly will not) provide a fix at the framework level. Hence, I am reporting this to Craft as I found it to affect the latest (`5.6.0`) version of Craft CMS. Leveraging a legitimate but maliciously crafted Yii `Behavior` class, it’s possible to trigger Remote Code Execution (RCE) via Reflection when the tainted `Behavior` is attached to a Yii `Component`, and an event is also fired on the tainted `Com
03 / Response
What to do next
- vendor patch
The original advisory lists fixed boundaries 5.8.21 for craftcms/cms. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
- vendor patch
The original advisory lists fixed boundaries 4.16.17 for craftcms/cms. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-255j-qw47-wjh5 ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.