# CVE-2026-91954: FreeRDP before 3.31.0 NULL Pointer Dereference via NSCodec

> A malicious RDP server can crash a FreeRDP client by sending crafted Surface Bits commands, causing a denial of service.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/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:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 15 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-91954, GHSA-32wp-qph9-89pm, GHSA-ffjr-p229-hpch, UBUNTU-CVE-2026-91954

## What is CVE-2026-91954?

CVE-2026-91954 is a high-severity vulnerability in Freerdp Freerdp, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

FreeRDP before 3.31.0 contains a null pointer dereference vulnerability in gdi_surface_bits when processing Surface Bits commands with NSCodec codec ID. A malicious RDP server can crash a FreeRDP client by sending a crafted Surface Bits command claiming to use NSCodec, even when the codec is disabled.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-91954?

It affects 1 product.


Products: Freerdp Freerdp.

## How do I fix CVE-2026-91954?

Upgrade to a fixed version.

## Is CVE-2026-91954 being exploited?

There is no known exploitation of CVE-2026-91954 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-2026-91954 and fix it if it is affected.

What it is: CVE-2026-91954 is a high-severity vulnerability in Freerdp Freerdp, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-91954 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-2026-91954/ (Markdown: https://insights.sbomify.com/CVE-2026-91954/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91954
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91954
- OSV: https://osv.dev/vulnerability/CVE-2026-91954

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91954/
Summaries are generated and may contain mistakes; the official description above is the record.