Deskflow: TLS multiplexer DoS on failed `SSL_accept`

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.

Problem type

Affected products

deskflow

deskflow

< 1.26.0.167 - AFFECTED

References

https://github.com/deskflow/deskflow/security/advisories/GHSA-3mxm-cgh2-6448

https://github.com/deskflow/deskflow/security/advisories/GHSA-3mxm-cgh2-6448

x_refsource_CONFIRM

https://github.com/deskflow/deskflow/commit/329783490bd16774ba903b84212467d20d76bfba

https://github.com/deskflow/deskflow/commit/329783490bd16774ba903b84212467d20d76bfba

x_refsource_MISC

JSON source

https://cveawg.mitre.org/api/cve/CVE-2026-44296

Click to expand

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    "dateUpdated": "2026-05-12T20:52:59.664Z",
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