# CVE-2026-91964: FreeRDP 2.0.0 through 3.30.0 Heap Buffer Overflow via RoutingToken

> A malicious RDP server can trigger a heap buffer overflow in FreeRDP clients, potentially leading to code execution or crashes.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/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:** 16 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-91964, GHSA-2vf2-grvj-6g8x, GHSA-f73m-4rv5-6gp4, UBUNTU-CVE-2026-91964

## What is CVE-2026-91964?

CVE-2026-91964 is a high-severity memory corruption vulnerability in 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 versions before 3.31.0 contain a heap-based buffer overflow in nego_send_negotiation_request when processing Server Redirection PDU messages with attacker-controlled LoadBalanceInfo fields. A malicious RDP server can trigger the overflow by sending an arbitrary-length field that gets written to a fixed 512-byte buffer without validation, causing client crashes or potential code execution when chained with memory disclosure.

Weakness: CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-91964?


## How do I fix CVE-2026-91964?

Upgrade to a fixed version.

## Is CVE-2026-91964 being exploited?

There is no known exploitation of CVE-2026-91964 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-91964 and fix it if it is affected.

What it is: CVE-2026-91964 is a high-severity memory corruption vulnerability in 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-2026-91964 in the wild and no public exploit code.

Affected product: 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-2026-91964/ (Markdown: https://insights.sbomify.com/CVE-2026-91964/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-91964
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-91964
- OSV: https://osv.dev/vulnerability/CVE-2026-91964

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-91964/
Summaries are generated and may contain mistakes; the official description above is the record.