---
id: CVE-2026-52769
title: YesWiki is a wiki system written in PHP
summary: >-
  YesWiki is a wiki system written in PHP. From version 4.6.2 to before version
  4.6.6, the POST /api/forms/{formId}/actor/inbox route - exposed publicly with
  acl:"public" - accepts an HTTP Signature header whose keyId parameter is a
  URL. H…
severity: high
cvss: 8.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L'
cwe:
  - CWE-918
vendor: YesWiki
product: yeswiki
affected:
  - 'yeswiki >= 4.6.2, < 4.6.6'
patched:
  - yeswiki/yeswiki 4.6.6
published: '2026-09-05'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T21:05:26.920'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-52769'
references:
  - url: >-
      http://github.com/YesWiki/yeswiki/commit/87e627f33e79879827a3669fee2aa1244612c487
    label: security-advisories@github.com
  - url: 'https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6'
    label: security-advisories@github.com
  - url: 'https://github.com/YesWiki/yeswiki/security/advisories/GHSA-vw42-752g-5mrp'
    label: security-advisories@github.com
  - url: 'https://github.com/YesWiki/yeswiki/security/advisories/GHSA-vw42-752g-5mrp'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://github.com/advisories/GHSA-vw42-752g-5mrp'
tags:
  - nvd
  - cve.org
  - exploit-available
  - ghsa
  - composer
epss: 0.00487
epssPercentile: 0.39324
aliases:
  - GHSA-vw42-752g-5mrp
ecosystem: composer
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-08T13:02:51.258242Z'
ingestedAt: '2026-07-09T21:52:34.690Z'
---

## Overview

YesWiki is a wiki system written in PHP. From version 4.6.2 to before version 4.6.6, the POST /api/forms/{formId}/actor/inbox route - exposed publicly with acl:"public" - accepts an HTTP Signature header whose keyId parameter is a URL. HttpSignatureService::verifySignature() parses the header and immediately makes a server-side HTTP GET to that URL, before any cryptographic verification or URL validation. An unauthenticated remote attacker can therefore make YesWiki issue arbitrary outbound HTTP requests to any host the server can reach - internal services, cloud-metadata endpoints (169.254.169.254), intranet-only admin panels, etc. - and read enough back via timing and error-message oracles to scan ports, enumerate services, and (on a real cloud instance) reach IAM metadata. The only deployment-side precondition is that ActivityPub be enabled on at least one Bazar form. This issue has been patched in version 4.6.6.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-52769)

Affected packages:

- `yeswiki/yeswiki >= 4.6.2, < 4.6.6`

Patched in:

- `yeswiki/yeswiki 4.6.6`

Source: https://github.com/advisories/GHSA-vw42-752g-5mrp