CVE-2020-15117: Denial of Service in Synergy

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-07-15 · updated 2026-06-17
Weakness: CWE-755

Description

In Synergy before version 1.12.0, a Synergy server can be crashed by receiving a kMsgHelloBack packet with a client name length set to 0xffffffff (4294967295) if the servers memory is less than 4 GB. It was verified that this issue does not cause a crash through the exception handler if the available memory of the Server is more than 4GB.

Affected products

Fedoraproject Fedora: 32, 33
symless Synergy: before 1.12.0 — fixed in 1.12.0

How to fix

Upgrade to a fixed version: symless Synergy 1.12.0. Check the vendor advisory for mitigations.

References

https://github.com/symless/synergy-core/commit/0a97c2be0da2d0df25cb86dfd642429e7a8bea39
https://github.com/symless/synergy-core/security/advisories/GHSA-chfm-333q-gfpp
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VFDEQED64YLWQK2TF73EMXZDYX7YT2DD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WAQYCMBWNVCIEM27NPIKK3DGJCNBYLAK/
https://github.com/symless/synergy-core/commit/0a97c2be0da2d0df25cb86dfd642429e7a8bea39
https://github.com/symless/synergy-core/security/advisories/GHSA-chfm-333q-gfpp
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VFDEQED64YLWQK2TF73EMXZDYX7YT2DD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WAQYCMBWNVCIEM27NPIKK3DGJCNBYLAK/

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