# CVE-2026-54538: xrdp: Pre-auth infinite loop via totalLength=0 in TS_SHARECONTROLHEADER

> Unauthenticated attackers can cause a denial of service in xrdp by sending crafted packets that trigger an infinite loop, exhausting CPU resources.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 Jul 2026
- **Updated:** 20 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-54538, GHSA-9j3q-9mvw-qv7j, UBUNTU-CVE-2026-54538

## What is CVE-2026-54538?

CVE-2026-54538 is a high-severity denial of service vulnerability in neutrinolabs xrdp, published on 20 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

xrdp is an open source RDP server. In versions 0.10.6 and prior, a n issue was discovered where the software fails to properly validate the totalLength field within the RDP protocol control header during packet reception. An unauthenticated remote attacker can exploit this vulnerability by sending a specially crafted packet that forces the xrdp process or thread into an infinite, CPU-bound loop. Because the internal pointer fails to advance and the deadlock prevention mechanism is bypassed for specific protocol data unit types, the process consumes excessive CPU resources indefinitely. This can render the xrdp service unavailable and potentially lead to system-wide resource exhaustion if multiple malicious connections are established. This issue has been fixed in version 0.10.6.1.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-54538?

It affects 1 product.


Products: Neutrinolabs Xrdp.

## How do I fix CVE-2026-54538?

Upgrade to a fixed version.

## Is CVE-2026-54538 being exploited?

There is no known exploitation of CVE-2026-54538 in the wild and no public exploit code.

## Other vulnerabilities in neutrinolabs xrdp

- [CVE-2026-41252](https://insights.sbomify.com/CVE-2026-41252/): xrdp: lib_palette_update Heap Buffer Overflow & RCE (critical 9.8)
- [CVE-2026-32105](https://insights.sbomify.com/CVE-2026-32105/): xrdp: RDP MAC signature (dataSignature) never verified on receive — integrity bypass in non-TLS mode (critical 9.3)
- [CVE-2026-44178](https://insights.sbomify.com/CVE-2026-44178/): xrdp: Channel Data Forwarding Fixed-Size Buffer Overflow (high 8.8)
- [CVE-2026-32107](https://insights.sbomify.com/CVE-2026-32107/): xrdp: Fail-open privilege drop in sesexec — child processes may execute as root if setuid fails (high 8.8)
- [CVE-2026-33689](https://insights.sbomify.com/CVE-2026-33689/): xrdp: Pre-authentication out-of-bounds reads in channel parsers (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54538 and fix it if it is affected.

What it is: CVE-2026-54538 is a high-severity denial of service vulnerability in neutrinolabs xrdp, published on 20 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-54538 in the wild and no public exploit code.

Affected product: neutrinolabs xrdp. 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-2026-54538/ (Markdown: https://insights.sbomify.com/CVE-2026-54538/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54538
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54538
- OSV: https://osv.dev/vulnerability/CVE-2026-54538

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54538/
Summaries are generated and may contain mistakes; the official description above is the record.