CVE-2020-15117: In Synergy before version 1.12.0, a Synergy server can be crashed by receiving a kMsgHelloBack packet with a c

Q: How do I fix CVE-2020-15117?

synergy: upgrade to 1.12.0; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2020-15117 being exploited?

CVE-2020-15117 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-15117 affect?

CVE-2020-15117 affects synergy, fedora. Severity is medium (CVSS 6.5). 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

Q: How urgent is CVE-2020-15117?

Priority 44/100. No elevated risk signals yet.

This month

MEDIUM 6.5UPGRADEMITIGATE

CVE-2020-15117 is a medium-severity flaw (CVSS 6.5) affecting synergy, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Weakness	CWE-755, CWE-754
Published	2020-07-15
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: fedoraproject · symless

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-07-15 18:15 UTCPublished CVE record published
2026-06-17 02:56 UTCUpdated Record last modified

symless synergy UPGRADE

Affected: < 1.12.0

Fixed in: 1.12.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy synergy || rpm -q synergy || synergy --version

2. UPGRADE to 1.12.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade synergy

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade synergy

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

fedoraproject fedora MITIGATE

Affected: 32 · 33

Fixed in: no fixed release known

Safe to downgrade to: a release before 32

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-15117?

synergy: upgrade to 1.12.0; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-15117 being exploited?

CVE-2020-15117 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-15117 affect?

CVE-2020-15117 affects synergy, fedora. Severity is medium (CVSS 6.5). 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

How urgent is CVE-2020-15117?

Priority 44/100. No elevated risk signals yet.

References

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