# CVE-2026-91949: FreeRDP 3.0.0 through 3.30.0 Protocol Negotiation Bypass

> Unauthenticated attackers can bypass RDSTLS transport restrictions in FreeRDP servers by manipulating protocol negotiation, allowing unauthorized TLS connections.

- **Severity:** Critical 9.2 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/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:** 15 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** ALSA-2026:73979, DEBIAN-CVE-2026-91949, GHSA-hcpv-8ff6-4xx8, GHSA-x7v6-xfx3-52j6, RHSA-2026:73979, RLSA-2026:73979, UBUNTU-CVE-2026-91949

## What is CVE-2026-91949?

CVE-2026-91949 is a critical vulnerability in Freerdp Freerdp, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

FreeRDP server versions before 3.31.0 contain a protocol negotiation bypass vulnerability that allows unauthenticated attackers to establish RDSTLS connections despite server policy disabling them. Attackers can send incompatible protocol requests, receive negotiation failures, then complete TLS handshake and enter RDSTLS to bypass pre-authentication transport restrictions.

Weakness: CWE-693 (Protection Mechanism Failure)

## Which versions are affected by CVE-2026-91949?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `freerdp` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp-devel` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp-libs` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp-server` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.13 |
| `libwinpr` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.13 |
| `libwinpr-devel` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp-debugsource` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp-devel` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp-libs` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp-libs-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp-server` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp-server-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `libwinpr` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `libwinpr-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `libwinpr-devel` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.13 |
| `freerdp` | Rocky Linux:10 | All versions | 2:3.10.3-12.el10_2.13 |

Products: Freerdp Freerdp.

## How do I fix CVE-2026-91949?

Upgrade to a fixed version.

## Is CVE-2026-91949 being exploited?

There is no known exploitation of CVE-2026-91949 in the wild and no public exploit code.

## Other vulnerabilities in Freerdp Freerdp

- [CVE-2021-37594](https://insights.sbomify.com/CVE-2021-37594/): Other in n/a (critical 9.8)
- [CVE-2021-37595](https://insights.sbomify.com/CVE-2021-37595/): Other in n/a (critical 9.8)
- [CVE-2026-67305](https://insights.sbomify.com/CVE-2026-67305/): FreeRDP Windows Client before 3.29.0 Heap Buffer Overflow via Cliprdr (critical 9.4)
- [CVE-2026-66402](https://insights.sbomify.com/CVE-2026-66402/): FreeRDP before 3.29.0 TLS Certificate Identity Validation Bypass (critical 9.3)
- [CVE-2026-67289](https://insights.sbomify.com/CVE-2026-67289/): FreeRDP before 3.29.0 HTTP Proxy Request Injection via Redirection (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-91949 and fix it if it is affected.

What it is: CVE-2026-91949 is a critical vulnerability in Freerdp Freerdp, published on 15 Sep 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-2026-91949 in the wild and no public exploit code.

Affected product: Freerdp Freerdp. 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-2026-91949/ (Markdown: https://insights.sbomify.com/CVE-2026-91949/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91949
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91949
- OSV: https://osv.dev/vulnerability/CVE-2026-91949

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91949/
Summaries are generated and may contain mistakes; the official description above is the record.