Flightctl-api: flightctl-remote-access: flightctl: unbounded tls handshake in conncontext can block accepting connections
Affects Red Hat Edge Manager 1's flightctl-api agent endpoint (port 7443) and remote access server. No fixed version is listed in the checked facts.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Not reported
Do first: Workaround: Schedule a recurrent check on the listener's Recv-Q and terminate idle connections when the queue is non-zero; restarting the server and blocking the malicious device at network level can recover service
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 40/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The flightctl API's remote access component contains a flaw in which a TLS handshake runs without a timeout during connection setup. An unauthenticated attacker can exploit this remotely, without logging in, by stalling the handshake so the affected listener stops accepting new connections, causing a denial of service.
Read the original description
A flaw was found in flightctl. A TLS handshake is performed synchronously in the HTTP server’s connection-context callback without a deadline. A network-reachable unauthenticated client can stall the handshake and prevent the affected listener from accepting new connections.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed, reachable over the network without a login · Unknown: Advisories don't say whether default setups are affected
- Reach10/20Shipped in major Linux distributions
- Severity7.5/10CVSS 7.5
- No patch5/5No patch listed yet
What would change the score
- Would score about 85 if added to CISA KEV
- Would score about 80 if CISA's SSVC rates exploitation active
- Would score about 45 if advisories confirm default setups are exposed
What to do
Workaround: Schedule a recurrent check on the listener's Recv-Q and terminate idle connections when the queue is non-zero; restarting the server and blocking the malicious device at network level can recover service
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-120399 (Flightctl-api: flightctl-remote-access: flightctl: unbounded tls handshake in conncontext can block accepting connections), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-120399 (entry last updated 2026-11-10): Affected: - Red Hat Red Hat Edge Manager 1: version range not reported - Red Hat Red Hat Edge Manager 1: version range not reported - Red Hat Red Hat Edge Manager 1: version range not reported - Red Hat Red Hat Edge Manager 1: version range not reported Fixed versions: none listed yet. Conditions (all must be true for the bug to be hit): - Affects flightctl-api (agent endpoint, port 7443) and the remote access server (source: https://bugzilla.redhat.com/show_bug.cgi?id=2564888) Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. Attacker needs: network access, no login, no user action. Workaround: Schedule a recurrent check on the listener's Recv-Q and terminate idle connections when the queue is non-zero; restarting the server and blocking the malicious device at network level can recover service (source: https://www.cve.org/CVERecord?id=CVE-2026-120399) CISA KEV: CVE-2026-120399 is not listed as of cve.now's last read. This KEV status is for CVE-2026-120399 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://bugzilla.redhat.com/show_bug.cgi?id=2564888 - https://access.redhat.com/security/cve/CVE-2026-120399 - https://www.cve.org/CVERecord?id=CVE-2026-120399 Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-120399 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-120399.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- rhem/flightctl-api-rhel10
Version range not reported
- rhem/flightctl-api-rhel9
Version range not reported
- rhem/flightctl-remote-access-rhel10
Version range not reported
- rhem/flightctl-remote-access-rhel9
Version range not reported
Evidence 4
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Write-ups · 1
Establishes: Technical detail and context.
- Report
Other links · 1
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-120399
Is CVE-2026-120399 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
A TLS handshake that never completes can block the accept loop, so the affected listener stops accepting new connections. The result is a denial of service.Source: bugzilla.redhat.com, access.redhat.com, cve.org
Am I affected, and how do I check?
The affected components are the flightctl-api agent endpoint on port 7443 and the remote access server in Red Hat Edge Manager 1. The checked facts give no version range, so check the vendor advisory for the exact affected builds and confirm whether these components are deployed.Source: bugzilla.redhat.com, access.redhat.com, cve.org
How do I fix CVE-2026-120399?
The checked facts name no fixed version, so no upgrade target can be given. Follow the vendor advisory for a fix and apply it when it is released.Source: bugzilla.redhat.com, access.redhat.com, cve.org
What if there's no patch?
Schedule a recurring check on the listener's Recv-Q and terminate idle connections whenever the queue is non-zero. Restarting the server and blocking the offending device at network level can restore service.Source: bugzilla.redhat.com, access.redhat.com, cve.org