CVE-2026-39959 — Tmds.DBus
HIGHCVE-2026-39959 is a high-severity (CVSS 7.1) CWE-290 vulnerability in Tmds.DBus. A fix is available for Tmds.DBus — see the affected versions and patch details below.
Tmds.DBus: malicious D-Bus peers can spoof signals, exhaust file descriptor resources, and cause denial of service
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-39959.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-39959 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
Tmds.DBus.NETTmds.DBus.Protocol.NETTmds.DBus.ProtocolReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Tmds.DBus and Tmds.DBus.Protocol are vulnerable to malicious D-Bus peers. A peer on the same bus can spoof signals by impersonating the owner of a well-known name, exhaust system resources or cause file descriptor spillover by sending messages with an excessive number of Unix file descriptors, and crash the application by sending malformed message bodies that cause unhandled exceptions on the SynchronizationContext.
Patches
The vulnerabilities are fixed in version 0.92.0. For Tmds.DBus.Protocol, the fixes are also backported to 0.21.3.
Workarounds
There are no known workarounds. Users should upgrade to a patched version.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Tmds.DBus | all versions | 0.92.0dotnet add package Tmds.DBus --version 0.92.0 |
| .NETNuGet | Tmds.DBus.Protocol | all versions | 0.21.3dotnet add package Tmds.DBus.Protocol --version 0.21.3 |
| .NETNuGet | Tmds.DBus.Protocol | ≥ 0.22.0&&< 0.92.0 | 0.92.0dotnet add package Tmds.DBus.Protocol --version 0.92.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Tmds.DBus, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Tmds.DBus to 0.92.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-39959 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-39959 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-39959. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-39959 in your dependencies?
O3 Security finds CVE-2026-39959 across NuGet dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.