CVE-2026-22542
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedAn attacker with access to the system's internal network can cause a denial of service on the system by making two concurrent connections through the Telnet service.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceA denial-of-service vulnerability exists in a system's Telnet service where an attacker with internal network access can trigger a DoS condition by establishing two concurrent Telnet connections, likely exploiting a race condition or resource handling flaw in the connection handling logic.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- Authentication
- X
- User interaction
- None
- Scope
- X
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify Telnet service statusCheck if the Telnet server daemon is running on the system. On Linux: 'systemctl status telnet' or 'ps aux | grep telnet'. On Windows: check if 'Telnet Service' is started via Services console or 'sc query telnet'.Affected if Telnet service is actively running and accepting connections.
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Identify Telnet daemon versionQuery the Telnet service version. For common Linux Telnet servers (like xinetd-based or systemd socket-activated): check the package version via 'dpkg -l | grep telnet' or 'rpm -q telnet-server'. For embedded/network devices, connect to the Telnet port and look for banner information using 'nc -v <target> 23' or 'telnet <target> 23'.Affected if The installed Telnet server version falls within any known affected version range (compare against vendor advisories for this CVE).
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Confirm Telnet port accessibilityVerify that TCP port 23 (or custom Telnet port) is listening and reachable. Run 'netstat -tuln | grep 23' or 'ss -tuln | grep 23' to confirm listening status. From an internal test host, confirm reachability: 'nmap -p 23 <target IP>' or 'telnet <target IP> 23'.Affected if Telnet port is open and accessible from internal network segments.
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Check for concurrent connection handlingReview system logs for evidence of Telnet connection handling issues. On Linux: 'journalctl -u telnet' or check /var/log/syslog for 'telnet' entries. Monitor active connections during normal operation: 'netstat -an | grep :23' or 'ss -an | grep :23'.Affected if System exhibits instability, crashes, or service interruption when two Telnet connections are established simultaneously (this would require testing in an isolated environment to confirm).
The system is likely affected if Telnet is enabled, accessible from the internal network, and the installed version matches the vulnerable range - the specific exploit requires two concurrent Telnet connections to trigger the DoS condition.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataIf Telnet is not required, disable the service entirely. If required, restrict network access to the Telnet port to trusted internal systems only and monitor for unusual connection patterns.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-22542 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-22542 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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