# CVE-2026-91956: FreeRDP before 3.31.0 Out-of-Bounds Read via URBDRC

> A malicious RDP server can trigger an out-of-bounds read in FreeRDP clients, causing a crash or potential memory disclosure.

- **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:** 18 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-91956, GHSA-hg4r-vv53-vwf8, GHSA-mh85-h6g9-mfcc, UBUNTU-CVE-2026-91956

## What is CVE-2026-91956?

CVE-2026-91956 is a high-severity memory corruption 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 an out-of-bounds read vulnerability in the URBDRC channel's func_get_ep_desc function that indexes interface arrays by position instead of protocol field InterfaceNumber. A malicious RDP server can send a crafted SELECT_CONFIGURATION message with permuted InterfaceNumber values to read past allocated heap memory and crash the client.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-91956?

It affects 1 product.


Products: Freerdp Freerdp.

## How do I fix CVE-2026-91956?

Upgrade to a fixed version.

## Is CVE-2026-91956 being exploited?

There is no known exploitation of CVE-2026-91956 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-2026-91956 and fix it if it is affected.

What it is: CVE-2026-91956 is a high-severity memory corruption 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-2026-91956 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-2026-91956/ (Markdown: https://insights.sbomify.com/CVE-2026-91956/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91956
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91956
- OSV: https://osv.dev/vulnerability/CVE-2026-91956

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91956/
Summaries are generated and may contain mistakes; the official description above is the record.