CVE-2021-33034

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.

• CWE-416

• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.4Mailing List, Patch, Vendor Advisory
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5c4c8c9544099bb9043a10a5318130a943e32fc3Mailing List, Patch, Vendor Advisory
• https://lists.debian.org/debian-lts-announce/2021/06/msg00019.htmlThird Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/06/msg00020.htmlThird Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GI7Z7UBWBGD3ABNIL2DC7RQDCGA4UVQW/
• https://sites.google.com/view/syzscope/kasan-use-after-free-read-in-hci_send_aclExploit, Third Party Advisory
• https://syzkaller.appspot.com/bug?id=2e1943a94647f7732dd6fc60368642d6e8dc91b1Exploit, Mailing List, Third Party Advisory
• https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.12.4Mailing List, Patch, Vendor Advisory
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5c4c8c9544099bb9043a10a5318130a943e32fc3Mailing List, Patch, Vendor Advisory
• https://lists.debian.org/debian-lts-announce/2021/06/msg00019.htmlThird Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/06/msg00020.htmlThird Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GI7Z7UBWBGD3ABNIL2DC7RQDCGA4UVQW/
• https://sites.google.com/view/syzscope/kasan-use-after-free-read-in-hci_send_aclExploit, Third Party Advisory
• https://syzkaller.appspot.com/bug?id=2e1943a94647f7732dd6fc60368642d6e8dc91b1Exploit, Mailing List, Third Party Advisory

Published

May 14, 2021

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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