CVE-2026-52766: Permission Flaw (CVSS 9.1)

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.

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CVSS v3.1 Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

EPSS — Exploit Prediction

0.0033

Probability of exploitation

0.26%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-276 Incorrect Default Permissions

CWE-862 Missing Authorization

References

Other References

https://github.com/YesWiki/yeswiki/commit/ed5b548a705c8091ba0282aaaba73ddda976abef https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6 https://github.com/YesWiki/yeswiki/security/advisories/GHSA-6x7x-gcmf-7r8x https://github.com/YesWiki/yeswiki/security/advisories/GHSA-6x7x-gcmf-7r8x

Frequently Asked Questions

What is CVE-2026-52766? +

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. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-52766? +

CVE-2026-52766 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0033, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-52766? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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