Red Hat Edge Manager 1: Use of Blocking Code in Single-threaded, Non-blocking Context
CVE-2026-120399 is a high-severity use of blocking code in single-threaded, non-blocking context vulnerability in Red Hat Edge Manager 1 from Red Hat, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 0.34% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Red Hat Edge Manager 1 you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Red Hat | Red Hat Edge Manager 1 | Not specified in the record | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (redhat.com).
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Blocking Code in Single-threaded, Non-blocking Context
The product uses a non-blocking model that relies on a single threaded process for features such as scalability, but it contains code that can block when it is invoked.
How developers prevent this class of flaw
- Generally speaking, blocking calls should be replaced with non-blocking alternatives that can be used asynchronously. Expensive computations should be passed off to worker threads, although the correct approach depends on the framework being used.
- For expensive computations, consider breaking them up into multiple smaller computations. Refer to the documentation of the framework being used for guidance.
More Use of Blocking Code in Single-threaded, Non-blocking Context vulnerabilities (CWE-1322)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in Red Hat Edge Manager 1
- 9.3 Critical severity
- 9.1 Critical severity
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