Craft CMS: Authorship spoofing in entries/save-entry via pre-check/post-mutation authorization gap

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.6 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-50279: 0.36% estimated exploitation activity in the next 30 days; percentile 30.33 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary EntriesController::actionSaveEntry() performs entry-edit permission checks before request-controlled author changes are applied to the model. The subsequent author mutation path accepts attacker-supplied authors / author parameters and allows the change when the current user is one of the old authors. Because the controller does not re-run authorization after mutating the author list, a low-privileged user can reassign an entry’s authorship to another user without holding the dedicated peer-author-change permission. Details The control flow begins in EntriesController.php:249. actionSaveEntry() loads the entry and enforces edit permissions before calling populateEntryModel(): The attacker-controlled source is in EntriesController.php:588: Entry::setAttributesFromRequest() in Entry.php:1124 extracts the new author IDs and applies them if canChangeAuthor() returns true: canChangeAuthor() at Entry.php:2789 allows the author change when the current user can view peer entries and…

Published by the source

2 Jul 2026, 18:45 UTC

Last modified by the source

2 Jul 2026, 18:45 UTC

Source last checked

26 Oct 2026, 14:49 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-qq2c-2q8j-jh27

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# Patch Next advisory brief: CVE-2026-50279

Advisory: Craft CMS: Authorship spoofing in `entries/save-entry` via pre-check/post-mutation authorization gap
IDs: CVE-2026-50279, GHSA-qq2c-2q8j-jh27
Record: https://patchnext.com/advisories/cve-2026-50279 (revision 1, source checked 26 Oct 2026, 14:49 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: craftcms/cms 5.9.21. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist craftcms/cms: affected >= 5.0.0-RC1, < 5.9.21; fixed in 5.9.21

## Suggested inspection (read-only)
- Packagist craftcms/cms: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on craftcms/cms.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-qq2c-2q8j-jh27 (GitHub-reviewed advisory GHSA-qq2c-2q8j-jh27 lists affected ranges: Packagist craftcms/cms >=5.0.0-RC1 <5.9.21)

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