# CVE-2026-91955: FreeRDP before 3.31.0 Denial of Service via Desktop Dimensions

> Remote attackers can crash the FreeRDP server by sending crafted RDP packets with invalid desktop dimensions, causing a denial of service.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/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:** 15 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-91955, GHSA-3hqr-g437-cr9w, GHSA-4464-r7qj-pgrx, UBUNTU-CVE-2026-91955

## What is CVE-2026-91955?

CVE-2026-91955 is a high-severity denial of service 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 before 3.31.0 fails to validate client-supplied DesktopWidth and DesktopHeight values during GCC negotiation, allowing remote attackers to crash the server. Attackers can send crafted RDP packets with zero or oversized dimensions to trigger division-by-zero or assertion failures in multifragment update capability calculations, terminating the server process.

Weakness: CWE-369 (Divide By Zero)

## Which versions are affected by CVE-2026-91955?

It affects 1 product.


Products: Freerdp Freerdp.

## How do I fix CVE-2026-91955?

Upgrade to a fixed version.

## Is CVE-2026-91955 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-91955 exists.

## 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-2026-91955 and fix it if it is affected.

What it is: CVE-2026-91955 is a high-severity denial of service 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-91955 exists.

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-2026-91955/ (Markdown: https://insights.sbomify.com/CVE-2026-91955/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91955
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91955
- OSV: https://osv.dev/vulnerability/CVE-2026-91955

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91955/
Summaries are generated and may contain mistakes; the official description above is the record.