Uncontrolled Recursion in Linux kernel - CVE-2026-63983
Published: July 20, 2026
Vulnerability identifier: #VU138667
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-63983
CWE-ID: CWE-674
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to uncontrolled recursion in netem packet duplication handling in the netem qdisc when processing duplicated packets through a qdisc tree containing another netem instance. A local user can trigger packet duplication to cause a denial of service.
Exploitation can exhaust stack or memory when packet duplication is enabled and duplicated packets are re-enqueued through another netem in the tree.
How to mitigate CVE-2026-63983
Install security update from vendor's repository.