# CVE-2026-28508: Idno: Unauthenticated SSRF via URL Unfurl Endpoint

> Unauthenticated attackers can bypass CSRF protection to force the Idno server to make arbitrary HTTP requests, potentially accessing internal networks and cloud metadata.

- **Severity:** Critical 9.2 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Mar 2026
- **Updated:** 6 Mar 2026
- **Also known as:** GHSA-fcrh-fqxh-6fx6

## What is CVE-2026-28508?

CVE-2026-28508 is a critical server-side request forgery vulnerability in idno, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Idno is a social publishing platform. Prior to version 1.6.4, a logic error in the API authentication flow causes the CSRF protection on the URL unfurl service endpoint to be trivially bypassed by any unauthenticated remote attacker. Combined with the absence of a login requirement on the endpoint itself, this allows an attacker to force the server to make arbitrary outbound HTTP requests to any host, including internal network addresses and cloud instance metadata services, and retrieve the response content. This issue has been patched in version 1.6.4.

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

## Which versions are affected by CVE-2026-28508?

2 open source packages ship an affected version, including idno/known. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `idno/known` | Packagist | All versions | 1.6.4 |
| `idno/known` | Packagist | All versions | 1.6.4 |

Products: Withknown Known.

## How do I fix CVE-2026-28508?

Upgrade idno/known to 1.6.4 or later.

## Is CVE-2026-28508 being exploited?

There is no known exploitation of CVE-2026-28508 in the wild and no public exploit code.

## Other vulnerabilities in idno

- [CVE-2026-26273](https://insights.sbomify.com/CVE-2026-26273/): Known affected by Account Takeover via Password Reset Token Leakage (critical 9.8)
- [CVE-2022-33011](https://insights.sbomify.com/CVE-2022-33011/): Known vulnerable to account takeover via host header injection attack in v1.3.1 (high 8.8)
- [CVE-2026-28507](https://insights.sbomify.com/CVE-2026-28507/): Idno: Remote Code Execution via Chained Import File Write and Template Path Traversal (high 8.6)
- [CVE-2022-32115](https://insights.sbomify.com/CVE-2022-32115/): Known vulnerable to code execution via SVG file in v1.3.1 (medium 6.1)
- [CVE-2022-31290](https://insights.sbomify.com/CVE-2022-31290/): Known v1.3.1 Cross-site Scripting (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-28508 and fix it if it is affected.

What it is: CVE-2026-28508 is a critical server-side request forgery vulnerability in idno, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-28508 in the wild and no public exploit code.

Affected packages and fixed versions:
- idno/known (Packagist): affected all versions; fixed in 1.6.4
- idno/known (Packagist): affected all versions; fixed in 1.6.4

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-2026-28508/ (Markdown: https://insights.sbomify.com/CVE-2026-28508/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28508
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28508
- OSV: https://osv.dev/vulnerability/CVE-2026-28508

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28508/
Summaries are generated and may contain mistakes; the official description above is the record.