---
title: "CVE-2026-52766: YesWiki vulnerable to unauthenticated arbitrary page deletion via `{{erasespamedcomments}}` action"
url: https://erroneo.us/security/cve/CVE-2026-52766/
description: "CVE-2026-52766 (yeswiki/yeswiki (Composer (PHP))): YesWiki is a wiki system written in PHP. Prior to version 4.6.6, the {{erasespamedcomments}} wiki action…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-09-04
date_modified: 2026-09-09
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-52766"
kev: false
cvss: 9.1
epss: 0.00579
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-52766: YesWiki vulnerable to unauthenticated arbitrary page deletion via `{{erasespamedcomments}}` action

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.6% , percentile 47: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 47% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes yeswiki/yeswiki (Composer (PHP)) < 4.6.6, fixed in 4.6.6 . Check your lockfile, including transitive dependencies.

## What it is

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 (defaultwriteacl='') 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.

## Affected packages

- Composer (PHP) `yeswiki/yeswiki` < 4.6.6 → fixed: 4.6.6

## Affected products (CVE record)

- YesWiki yeswiki: < 4.6.6

## Severity

- GitHub_M CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H`
- GitHub CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 0.58% probability of exploitation activity in the next 30 days; percentile 47.

## Sources

- [GitHub Advisory GHSA-6x7x-gcmf-7r8x](https://github.com/advisories/GHSA-6x7x-gcmf-7r8x)
- [CVE.org record CVE-2026-52766](https://www.cve.org/CVERecord?id=CVE-2026-52766)
- [NVD entry CVE-2026-52766](https://nvd.nist.gov/vuln/detail/CVE-2026-52766)
- [github.com](https://github.com/YesWiki/yeswiki/security/advisories/GHSA-6x7x-gcmf-7r8x)
- [github.com](https://github.com/YesWiki/yeswiki/commit/ed5b548a705c8091ba0282aaaba73ddda976abef)
- [github.com](https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6)

---
Source page: https://erroneo.us/security/cve/CVE-2026-52766/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt