# CVE-2026-63096: Dendrite 0.13.8 SSRF via Unauthenticated Legacy Media Download Endpoint

> Unauthenticated attackers can exploit an SSRF vulnerability in Dendrite to scan internal networks and leak internal IP addresses via the legacy media download endpoint.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/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:** No
- **Published:** 17 Jul 2026
- **Updated:** 28 Jul 2026
- **Also known as:** GHSA-jrcq-4ccj-6fr8

## What is CVE-2026-63096?

CVE-2026-63096 is a medium-severity server-side request forgery vulnerability in matrix-org dendrite, published on 17 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Dendrite through 0.13.8 contains a server-side request forgery vulnerability that allows unauthenticated attackers to cause the server to open outbound TLS connections to arbitrary hosts and ports by supplying an unvalidated serverName parameter to the legacy media download endpoint. Attackers can exploit distinguishable error response classes and leaked internal IP addresses in error messages to perform blind port scanning and enumerate internal network topology.

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

## Which versions are affected by CVE-2026-63096?


## How do I fix CVE-2026-63096?

No fix has been published for CVE-2026-63096 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-63096 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-63096 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63096 and fix it if it is affected.

What it is: CVE-2026-63096 is a medium-severity server-side request forgery vulnerability in matrix-org dendrite, published on 17 Jul 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-2026-63096 exists.

Affected product: matrix-org dendrite. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-63096/ (Markdown: https://insights.sbomify.com/CVE-2026-63096/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63096
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63096
- OSV: https://osv.dev/vulnerability/CVE-2026-63096

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63096/
Summaries are generated and may contain mistakes; the official description above is the record.