CVE-2026-52766: YesWiki is a wiki system written in PHP. Prior to version 4.6.6, the {{erasespamedcomments}} wiki action (actions/EraseSpamedCommentsAction.

CVE-2026-52766 · Severity: critical · CVSS 9.1 · Published 2026-09-05

YesWiki, a collaborative wiki platform, contains a security flaw that allows anyone to permanently delete any page on the site without needing an administrator account. An attacker could use this to remove the home page, administrative settings, or content created by other users, leading to significant data loss and service disruption. This issue is particularly severe on new installations where default settings allow public access to the vulnerable feature.

Technologies: yeswiki/yeswiki (Packagist), YesWiki. Vendors: Packagist, YesWiki.

Quick answers

Is CVE-2026-52766 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-52766 being exploited in the wild.
How severe is CVE-2026-52766?
Critical severity, with a CVSS score of 9.1, published 5 September 2026.
Which products and versions are affected?
yeswiki/yeswiki (Packagist) < 4.6.6, ECOSYSTEM:introduced=0,fixed=4.6.6; YesWiki < 4.6.6.
Is there a fix for CVE-2026-52766?
Yes. yeswiki/yeswiki (Packagist): upgrade to 4.6.6 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-52766 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-52766?
Check whether you run yeswiki/yeswiki (Packagist) or YesWiki at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • yeswiki/yeswiki (Packagist): upgrade to 4.6.6 or later
    composer require yeswiki/yeswiki:^4.6.6

Technical details

YesWiki contains a missing authorization vulnerability in the `{{erasespamedcomments}}` action (located in `actions/EraseSpamedCommentsAction.php`). The action processes a `suppr[]` array from POST requests and invokes `PageManager::deleteOrphaned()` without verifying if the user has administrative privileges or ownership of the target pages. Furthermore, the default Access Control List (ACL) configuration in YesWiki grants access to this action to all users, including anonymous ones. An attacker can exploit this by creating a page containing the action and then sending a crafted POST request to delete any page in the database, including system-critical pages. The vulnerability is addressed in version 4.6.6.

Affected products

  • YesWiki yeswiki/yeswiki < 4.6.6

Identifiers

  • CVE-2026-52766
  • GHSA-6x7x-gcmf-7r8x

Timeline

  • 2026-06-02: disclosed
  • 2026-07-09: advisory
  • 2026-07-09: patched: Fixed in version 4.6.6

References

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