{"id":"CVE-2023-4623","title":"A use-after-free vulnerability in the Linux kernel's net/sched: sch_hfsc (HFSC qdisc traffic control) component can be exploited to achieve local privilege escalation.\n\nIf a class with a link-sharing curve (i.e","summary":"A use-after-free vulnerability in the Linux kernel's net/sched: sch_hfsc (HFSC qdisc traffic control) component can be exploited to achieve local privilege escalation.\n\nIf a class with a link-sharing curve (i.e. with the HFSC_FSC flag se…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-416","CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 2.6.12, < 4.14.327","linux_kernel >= 4.15, < 4.19.295","linux_kernel >= 4.20, < 5.4.257","linux_kernel >= 5.5, < 5.10.195","linux_kernel >= 5.11, < 5.15.132","linux_kernel >= 5.16, < 6.1.53","linux_kernel >= 6.2, < 6.4.16","linux_kernel >= 6.5, < 6.5.3","debian_linux = 10.0"],"patched":["linux_kernel 6.5.3"],"published":"2023-09-06","updated":"2026-10-14","sourceUpdated":"2026-10-14T22:17:17.570","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2023-4623","references":[{"url":"http://packetstormsecurity.com/files/175963/Kernel-Live-Patch-Security-Notice-LSN-0099-1.html","label":"cve-coordination@google.com"},{"url":"https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b3d26c5702c7d6c45456326e56d2ccf3f103e60f","label":"cve-coordination@google.com"},{"url":"https://kernel.dance/b3d26c5702c7d6c45456326e56d2ccf3f103e60f","label":"cve-coordination@google.com"},{"url":"https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html","label":"cve-coordination@google.com"},{"url":"https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html","label":"cve-coordination@google.com"},{"url":"http://packetstormsecurity.com/files/175963/Kernel-Live-Patch-Security-Notice-LSN-0099-1.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b3d26c5702c7d6c45456326e56d2ccf3f103e60f","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://kernel.dance/b3d26c5702c7d6c45456326e56d2ccf3f103e60f","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-398330.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-769027.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-794697.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd"],"epss":0.00282,"epssPercentile":0.19282,"ingestedAt":"2026-10-14T23:00:02.002Z","slug":"CVE-2023-4623","body":"## Overview\n\nA use-after-free vulnerability in the Linux kernel's net/sched: sch_hfsc (HFSC qdisc traffic control) component can be exploited to achieve local privilege escalation.\n\nIf a class with a link-sharing curve (i.e. with the HFSC_FSC flag set) has a parent without a link-sharing curve, then init_vf() will call vttree_insert() on the parent, but vttree_remove() will be skipped in update_vf(). This leaves a dangling pointer that can cause a use-after-free.\n\nWe recommend upgrading past commit b3d26c5702c7d6c45456326e56d2ccf3f103e60f.\n\n## Affected\n\n- `linux_kernel >= 2.6.12, < 4.14.327`\n- `linux_kernel >= 4.15, < 4.19.295`\n- `linux_kernel >= 4.20, < 5.4.257`\n- `linux_kernel >= 5.5, < 5.10.195`\n- `linux_kernel >= 5.11, < 5.15.132`\n- `linux_kernel >= 5.16, < 6.1.53`\n- `linux_kernel >= 6.2, < 6.4.16`\n- `linux_kernel >= 6.5, < 6.5.3`\n- `debian_linux = 10.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.5.3`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}