# CVE-2026-44296: Deskflow: TLS multiplexer DoS on failed `SSL_accept`

> Remote unauthenticated attackers can cause denial of service in Deskflow by sending malformed TLS handshakes, stalling input delivery for all connected users.

- **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:** 12 May 2026
- **Updated:** 13 May 2026
- **Also known as:** DEBIAN-CVE-2026-44296, GHSA-3mxm-cgh2-6448, UBUNTU-CVE-2026-44296

## What is CVE-2026-44296?

CVE-2026-44296 is a high-severity denial of service vulnerability in deskflow, published on 12 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Deskflow is a keyboard and mouse sharing app. Prior to 1.26.0.167, a remote, unauthenticated denial of service (DoS) vulnerability affects Deskflow servers running with TLS enabled (the default). When any TCP peer connects to the listening port and its first bytes do not parse as a valid TLS ClientHello, SecureSocket::secureAccept enters its fatal-error branch and calls Arch::sleep(1) (a blocking 1-second sleep) on the multiplexer worker thread. That thread services every socket on the server, including established TLS clients delivering mouse motion, keyboard events, and clipboard updates. A single failed handshake therefore stalls input delivery to all connected screens for ~1 second, and a sustained drip of malformed connections (≥ 1/s) makes the server effectively unusable while the attack persists. This vulnerability is fixed in 1.26.0.167.

Weakness: CWE-405 (Asymmetric Resource Consumption (Amplification)), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-44296?


## How do I fix CVE-2026-44296?

Upgrade to a fixed version.

## Is CVE-2026-44296 being exploited?

There is no known exploitation of CVE-2026-44296 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44296 and fix it if it is affected.

What it is: CVE-2026-44296 is a high-severity denial of service vulnerability in deskflow, published on 12 May 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-2026-44296 in the wild and no public exploit code.

Affected product: deskflow. 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-2026-44296/ (Markdown: https://insights.sbomify.com/CVE-2026-44296/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44296
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44296
- OSV: https://osv.dev/vulnerability/CVE-2026-44296

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44296/
Summaries are generated and may contain mistakes; the official description above is the record.