# CVE-2026-55193: FreeRDP: Heap-buffer-overflow write in TS Gateway RPC fragment receive due to uncapped bind_ack max_xmit_frag

> A heap-buffer-overflow in FreeRDP allows a malicious gateway to crash the client or execute code via crafted RPC fragments.

- **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:** 19 Aug 2026
- **Updated:** 27 Aug 2026
- **Also known as:** ALSA-2026:66347, ALSA-2026:66349, ALSA-2026:69387, CLSA-2026-1792767913, CLSA-2026-1792768177, DEBIAN-CVE-2026-55193, GHSA-7rp4-66mc-j9vx, OESA-2026-4367, OESA-2026-4368, OESA-2026-4369, OESA-2026-4370, RHSA-2026:66347, RHSA-2026:66349, RHSA-2026:69387, RHSA-2026:72479, RHSA-2026:72481, RHSA-2026:73026, RHSA-2026:73027, RHSA-2026:73068, RHSA-2026:74470, RHSA-2026:74610, RLSA-2026:66347, RLSA-2026:66349, RLSA-2026:69387, UBUNTU-CVE-2026-55193

## What is CVE-2026-55193?

CVE-2026-55193 is a high-severity memory corruption vulnerability in Freerdp Freerdp, published on 19 Aug 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 is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, FreeRDP clients using TS Gateway accept a server-controlled max_xmit_frag value in libfreerdp/core/gateway/rpc_bind.c without bounding it to the 4088-byte ReceiveFragment allocation. A malicious gateway can advertise 65535 and then send a response fragment of the same length, causing rpc_channel_read in libfreerdp/core/gateway/rpc.c to write up to 65535 bytes into the smaller ReceiveFragment buffer. This can crash the client and may permit code execution through attacker-controlled heap corruption. This issue is fixed in version 3.27.0.

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

## Which versions are affected by CVE-2026-55193?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `freerdp` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp-devel` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp-libs` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp-server` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.11 |
| `libwinpr` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.11 |
| `libwinpr-devel` | AlmaLinux:10 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp` | AlmaLinux:8 | All versions | 2:2.11.7-13.el8_10 |
| `freerdp-devel` | AlmaLinux:8 | All versions | 2:2.11.7-13.el8_10 |
| `freerdp-libs` | AlmaLinux:8 | All versions | 2:2.11.7-13.el8_10 |
| `libwinpr` | AlmaLinux:8 | All versions | 2:2.11.7-13.el8_10 |
| `libwinpr-devel` | AlmaLinux:8 | All versions | 2:2.11.7-13.el8_10 |
| `freerdp` | AlmaLinux:9 | All versions | 2:2.11.7-7.el9_8.7 |
| `freerdp-devel` | AlmaLinux:9 | All versions | 2:2.11.7-7.el9_8.7 |
| `freerdp-libs` | AlmaLinux:9 | All versions | 2:2.11.7-7.el9_8.7 |
| `libwinpr` | AlmaLinux:9 | All versions | 2:2.11.7-7.el9_8.7 |
| `libwinpr-devel` | AlmaLinux:9 | All versions | 2:2.11.7-7.el9_8.7 |
| `freerdp` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp-debugsource` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp-devel` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp-libs` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp-libs-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp-server` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp-server-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `libwinpr` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `libwinpr-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `libwinpr-devel` | Red Hat:enterprise_linux:10.2 | All versions | 2:3.10.3-12.el10_2.11 |
| `freerdp` | Red Hat:enterprise_linux:8::appstream | All versions | 2:2.11.7-13.el8_10 |
| `freerdp-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 2:2.11.7-13.el8_10 |
| `freerdp-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 2:2.11.7-13.el8_10 |
| `freerdp-libs` | Red Hat:enterprise_linux:8::appstream | All versions | 2:2.11.7-13.el8_10 |
| `freerdp-libs-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 2:2.11.7-13.el8_10 |
| `libwinpr` | Red Hat:enterprise_linux:8::appstream | All versions | 2:2.11.7-13.el8_10 |
| `libwinpr-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 2:2.11.7-13.el8_10 |
| `libwinpr-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 2:2.11.7-13.el8_10 |
| `freerdp-debuginfo` | Red Hat:enterprise_linux:8::crb | All versions | 2:2.11.7-13.el8_10 |
| `freerdp-debugsource` | Red Hat:enterprise_linux:8::crb | All versions | 2:2.11.7-13.el8_10 |
| `freerdp-devel` | Red Hat:enterprise_linux:8::crb | All versions | 2:2.11.7-13.el8_10 |
| `freerdp-libs-debuginfo` | Red Hat:enterprise_linux:8::crb | All versions | 2:2.11.7-13.el8_10 |
| `libwinpr-debuginfo` | Red Hat:enterprise_linux:8::crb | All versions | 2:2.11.7-13.el8_10 |

Products: Freerdp Freerdp.

## How do I fix CVE-2026-55193?

Upgrade to a fixed version.

## Is CVE-2026-55193 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55193 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-2026-55193 and fix it if it is affected.

What it is: CVE-2026-55193 is a high-severity memory corruption vulnerability in Freerdp Freerdp, published on 19 Aug 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55193 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-2026-55193/ (Markdown: https://insights.sbomify.com/CVE-2026-55193/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-55193
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-55193
- OSV: https://osv.dev/vulnerability/CVE-2026-55193

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-55193/
Summaries are generated and may contain mistakes; the official description above is the record.