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

> Unauthenticated attackers can trigger server-side requests to internal resources via ActivityPub keyId, enabling port scanning and metadata access.

- **Severity:** High 8.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Sep 2026
- **Updated:** 8 Sep 2026
- **Also known as:** GHSA-vw42-752g-5mrp

## What is CVE-2026-52769?

CVE-2026-52769 is a high-severity server-side request forgery vulnerability in yeswiki, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-52769?

2 open source packages ship an affected version, including yeswiki/yeswiki.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `yeswiki/yeswiki` | Packagist | From 4.6.2 | 4.6.6 |
| `yeswiki/yeswiki` | Packagist | From 4.6.2 | 4.6.6 |

## How do I fix CVE-2026-52769?

Upgrade yeswiki/yeswiki to 4.6.6 or later.

## Is CVE-2026-52769 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-52769 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-52769 and fix it if it is affected.

What it is: CVE-2026-52769 is a high-severity server-side request forgery vulnerability in yeswiki, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-52769 exists.

Affected packages and fixed versions:
- yeswiki/yeswiki (Packagist): affected from 4.6.2; fixed in 4.6.6
- yeswiki/yeswiki (Packagist): affected from 4.6.2; fixed in 4.6.6

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-52769/ (Markdown: https://insights.sbomify.com/CVE-2026-52769/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52769
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52769
- OSV: https://osv.dev/vulnerability/CVE-2026-52769

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-52769/
Summaries are generated and may contain mistakes; the official description above is the record.