CVE-2026-52766 YesWiki: Unauthenticated arbitrary page deletion via `{{erasespamedcomments}}` action
Unauthenticated attackers can delete arbitrary wiki pages due to missing authorization checks in the erasespamedcomments action.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-52766?
CVE-2026-52766 is a critical missing authorization vulnerability in yeswiki, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
YesWiki is a wiki system written in PHP. Prior to version 4.6.6, the {{erasespamedcomments}} wiki action (actions/EraseSpamedCommentsAction.php) accepts a suppr[] array from POST and deletes every wiki page whose tag appears in that array, with no authorization check anywhere in the action body or in the page-deletion path it invokes. Combined with YesWiki's allow-by-default action ACL model, any user who has page write access, which is the default for everyone (default_write_acl='*') on a fresh install can permanently delete arbitrary wiki pages, including the front page, admin pages, and pages owned by other users. This issue has been patched in version 4.6.6.
Which versions are affected by CVE-2026-52766?
2 open source packages ship an affected version, including yeswiki/yeswiki.
| Package | Affected | Fixed in |
|---|---|---|
yeswiki/yeswiki Packagist | All versions | 4.6.6 |
yeswiki/yeswiki Packagist | All versions | 4.6.6 |
How do I fix CVE-2026-52766?
Upgrade yeswiki/yeswiki to 4.6.6 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-52766 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-52766 exists.
Sources
Also known as GHSA-6x7x-gcmf-7r8x.