{"id":"CVE-2023-4921","title":"A use-after-free vulnerability in the Linux kernel's net/sched: sch_qfq component can be exploited to achieve local privilege escalation.\n\nWhen the plug qdisc is used as a class of the qfq qdisc, sending network packets triggers use-afte…","summary":"A use-after-free vulnerability in the Linux kernel's net/sched: sch_qfq component can be exploited to achieve local privilege escalation.\n\nWhen the plug qdisc is used as a class of the qfq qdisc, sending network packets triggers use-afte…","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"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 3.8, < 4.14.326","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, < 6.1.54","linux_kernel >= 6.2, < 6.5.4","debian_linux = 10.0"],"patched":["linux_kernel 6.5.4"],"published":"2023-09-12","updated":"2026-10-14","sourceUpdated":"2026-10-14T22:17:18.763","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2023-4921","references":[{"url":"https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8fc134fee27f2263988ae38920bc03da416b03d8","label":"cve-coordination@google.com"},{"url":"https://kernel.dance/8fc134fee27f2263988ae38920bc03da416b03d8","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":"https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8fc134fee27f2263988ae38920bc03da416b03d8","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://kernel.dance/8fc134fee27f2263988ae38920bc03da416b03d8","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","cve.org"],"epss":0.00418,"epssPercentile":0.34476,"ingestedAt":"2026-10-14T23:00:02.003Z","ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2024-05-10T04:00:09.695048Z"},"slug":"CVE-2023-4921","body":"## Overview\n\nA use-after-free vulnerability in the Linux kernel's net/sched: sch_qfq component can be exploited to achieve local privilege escalation.\n\nWhen the plug qdisc is used as a class of the qfq qdisc, sending network packets triggers use-after-free in qfq_dequeue() due to the incorrect .peek handler of sch_plug and lack of error checking in agg_dequeue().\n\nWe recommend upgrading past commit 8fc134fee27f2263988ae38920bc03da416b03d8.\n\n## Affected\n\n- `linux_kernel >= 3.8, < 4.14.326`\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, < 6.1.54`\n- `linux_kernel >= 6.2, < 6.5.4`\n- `debian_linux = 10.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.5.4`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}