{"id":"CVE-2021-33034","title":"In the Linux kernel before 5.12.4, net/bluetooth/hci_event.c has a use-after-free when destroying an hci_chan, aka CID-5c4c8c954409","summary":"In the Linux kernel before 5.12.4, net/bluetooth/hci_event.c has a use-after-free when destroying an hci_chan, aka CID-5c4c8c954409. This leads to writing an arbitrary value.","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 < 4.4.269","linux_kernel >= 4.5, < 4.9.269","linux_kernel >= 4.10, < 4.14.233","linux_kernel >= 4.15, < 4.19.191","linux_kernel >= 4.20, < 5.4.119","linux_kernel >= 5.5, < 5.10.37","linux_kernel >= 5.11, < 5.11.21","linux_kernel >= 5.12, < 5.12.4","fedora = 34","debian_linux = 9.0"],"patched":["linux_kernel 5.12.4"],"published":"2021-05-14","updated":"2026-08-13","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-33034","references":[{"url":"https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.4","label":"cve@mitre.org"},{"url":"https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5c4c8c9544099bb9043a10a5318130a943e32fc3","label":"cve@mitre.org"},{"url":"https://lists.debian.org/debian-lts-announce/2021/06/msg00019.html","label":"cve@mitre.org"},{"url":"https://lists.debian.org/debian-lts-announce/2021/06/msg00020.html","label":"cve@mitre.org"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GI7Z7UBWBGD3ABNIL2DC7RQDCGA4UVQW/","label":"cve@mitre.org"},{"url":"https://sites.google.com/view/syzscope/kasan-use-after-free-read-in-hci_send_acl","label":"cve@mitre.org"},{"url":"https://syzkaller.appspot.com/bug?id=2e1943a94647f7732dd6fc60368642d6e8dc91b1","label":"cve@mitre.org"},{"url":"https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.4","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5c4c8c9544099bb9043a10a5318130a943e32fc3","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2021/06/msg00019.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2021/06/msg00020.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GI7Z7UBWBGD3ABNIL2DC7RQDCGA4UVQW/","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://sites.google.com/view/syzscope/kasan-use-after-free-read-in-hci_send_acl","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://syzkaller.appspot.com/bug?id=2e1943a94647f7732dd6fc60368642d6e8dc91b1","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd","exploit-available"],"epss":0.00819,"epssPercentile":0.55708,"ingestedAt":"2026-08-13T20:06:14.938Z","exploits":{"github":1,"githubRepos":["https://github.com/Trinadh465/device_renesas_kernel_AOSP10_r33_CVE-2021-33034"],"checkedAt":"2026-09-24T07:52:47.969Z"},"exploitAvailable":true,"slug":"CVE-2021-33034","body":"## Overview\n\nIn the Linux kernel before 5.12.4, net/bluetooth/hci_event.c has a use-after-free when destroying an hci_chan, aka CID-5c4c8c954409. This leads to writing an arbitrary value.\n\n## Affected\n\n- `linux_kernel < 4.4.269`\n- `linux_kernel >= 4.5, < 4.9.269`\n- `linux_kernel >= 4.10, < 4.14.233`\n- `linux_kernel >= 4.15, < 4.19.191`\n- `linux_kernel >= 4.20, < 5.4.119`\n- `linux_kernel >= 5.5, < 5.10.37`\n- `linux_kernel >= 5.11, < 5.11.21`\n- `linux_kernel >= 5.12, < 5.12.4`\n- `fedora = 34`\n- `debian_linux = 9.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 5.12.4`","depth":"midnight","depthScore":55,"depthScoreParts":{"impact":42.9,"likelihood":0.2,"exploitation":12,"ransomware":0},"changes":[{"seq":4521,"id":"CVE-2021-33034","ts":1788887187310,"field":"exploit_available","old":"false","new":"true"},{"seq":3404,"id":"CVE-2021-33034","ts":1788886305000,"field":"exploit_available","old":"true","new":"false"},{"seq":2259,"id":"CVE-2021-33034","ts":1788882974509,"field":"exploit_available","old":"false","new":"true"},{"seq":1288,"id":"CVE-2021-33034","ts":1788882386302,"field":"exploit_available","old":"true","new":"false"},{"seq":402,"id":"CVE-2021-33034","ts":1788881821978,"field":"exploit_available","old":"false","new":"true"}]}