CVE-2026-52769

CVE-2026-52769 · YesWiki: Unauthenticated Server-Side Request Forgery via ActivityPub `Signature.keyId`

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 8.3 · High · EPSS 0.5% · Fix available

Published

2026-09-04T23:40:58.793Z

Updated

2026-09-08T13:03:22.748Z

Stack: php

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