Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-124737 Overview
A flaw was found in BusyBox. When the TFTP (Trivial File Transfer Protocol) client requests a custom small block size and receives a standard response, it falls back to the default block size without resizing the allocated memory buffer. A malicious TFTP server can exploit this issue by sending standard-sized network packets during a transfer, causing a heap buffer overflow. This flaw allows an attacker to achieve arbitrary code execution or cause a Denial of Service (DoS) by crashing the application.
Critical Impact
Affected Products
- Red Hat BusyBox: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-11: CVE-2026-124737 published to the National Vulnerability Database by secalert@redhat.com
- 2026-11-11: last updated in the NVD database
Technical Details for CVE-2026-124737
Vulnerability Analysis
CVE-2026-124737 is a Out of Bounds Write weakness (CWE-787: Out of Bounds Write) in Red Hat BusyBox. Based on its CVSS vector, the flaw can be reached over the network, needs no login, and relies on a user taking an action. The program writes past the end of a buffer, a common path to code execution.
With a CVSS base score of 7.5, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The weakness is classified as CWE-787: Out of Bounds Write. The program writes past the end of a buffer, a common path to code execution.
Attack Vector
Based on the CVSS vector, the flaw can be reached over the network, needs no login, and relies on a user taking an action. Attack complexity is high complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Detection Methods for CVE-2026-124737
Detection Strategies
- Inventory every instance of Red Hat BusyBox and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward Red Hat BusyBox application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-124737
Immediate Actions Required
- Apply the fixed version of Red Hat BusyBox named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for Red Hat BusyBox.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
- CWE-787: Out of Bounds Write More CVEs with this weakness
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
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