CVE-2026-52769

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-05 00:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-08 21:05 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.5% in the next 30 days (EPSS).
• Severity: 8.3 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-09-05 00:17 UTC

Last modified

2026-09-08 21:05 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-918 · Server-side request forgery

Record status

Deferred

Attack profile CVSS 3.1 · 8.3

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

Low

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-52769.md and follow it. Check whether this project is affected by CVE-2026-52769. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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