{"cve":"CVE-2021-47588","nvd":{"published":"2024-06-19T15:15:53.383","modified":"2026-08-04T10:17:09.910","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsit: do not call ipip6_dev_free() from sit_init_net()\n\nipip6_dev_free is sit dev->priv_destructor, already called\nby register_netdevice() if something goes wrong.\n\nAlternative would be to make ipip6_dev_free() robust against\nmultiple invocations, but other drivers do not implement this\nstrategy.\n\nsyzbot reported:\n\ndst_release underflow\nWARNING: CPU: 0 PID: 5059 at net/core/dst.c:173 dst_release+0xd8/0xe0 net/core/dst.c:173\nModules linked in:\nCPU: 1 PID: 5059 Comm: syz-executor.4 Not tainted 5.16.0-rc5-syzkaller #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011\nRIP: 0010:dst_release+0xd8/0xe0 net/core/dst.c:173\nCode: 4c 89 f2 89 d9 31 c0 5b 41 5e 5d e9 da d5 44 f9 e8 1d 90 5f f9 c6 05 87 48 c6 05 01 48 c7 c7 80 44 99 8b 31 c0 e8 e8 67 29 f9 <0f> 0b eb 85 0f 1f 40 00 53 48 89 fb e8 f7 8f 5f f9 48 83 c3 a8 48\nRSP: 0018:ffffc9000aa5faa0 EFLAGS: 00010246\nRAX: d6894a925dd15a00 RBX: 00000000ffffffff RCX: 0000000000040000\nRDX: ffffc90005e19000 RSI: 000000000003ffff RDI: 0000000000040000\nRBP: 0000000000000000 R08: ffffffff816a1f42 R09: ffffed1017344f2c\nR10: ffffed1017344f2c R11: 0000000000000000 R12: 0000607f462b1358\nR13: 1ffffffff1bfd305 R14: ffffe8ffffcb1358 R15: dffffc0000000000\nFS:  00007f66c71a2700(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007f88aaed5058 CR3: 0000000023e0f000 CR4: 00000000003506f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n <TASK>\n dst_cache_destroy+0x107/0x1e0 net/core/dst_cache.c:160\n ipip6_dev_free net/ipv6/sit.c:1414 [inline]\n sit_init_net+0x229/0x550 net/ipv6/sit.c:1936\n ops_init+0x313/0x430 net/core/net_namespace.c:140\n setup_net+0x35b/0x9d0 net/core/net_namespace.c:326\n copy_net_ns+0x359/0x5c0 net/core/net_namespace.c:470\n create_new_namespaces+0x4ce/0xa00 kernel/nsproxy.c:110\n unshare_nsproxy_namespaces+0x11e/0x180 kernel/nsproxy.c:226\n ksys_unshare+0x57d/0xb50 kernel/fork.c:3075\n __do_sys_unshare kernel/fork.c:3146 [inline]\n __se_sys_unshare kernel/fork.c:3144 [inline]\n __x64_sys_unshare+0x34/0x40 kernel/fork.c:3144\n do_syscall_x64 arch/x86/entry/common.c:50 [inline]\n do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80\n entry_SYSCALL_64_after_hwframe+0x44/0xae\nRIP: 0033:0x7f66c882ce99\nCode: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48\nRSP: 002b:00007f66c71a2168 EFLAGS: 00000246 ORIG_RAX: 0000000000000110\nRAX: ffffffffffffffda RBX: 00007f66c893ff60 RCX: 00007f66c882ce99\nRDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000048040200\nRBP: 00007f66c8886ff1 R08: 0000000000000000 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000\nR13: 00007fff6634832f R14: 00007f66c71a2300 R15: 0000000000022000\n </TASK>","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/44a6c846bc3a7efe7d394bab8b2ae3b7f580e190","https://git.kernel.org/stable/c/4e1797914d8f223726ff6ae5ece4f97d73f21bab","https://git.kernel.org/stable/c/6f46c59e60b64620d5d386c8ee2eaa11ebe3b595","https://git.kernel.org/stable/c/ad0ed314d6167b212939e3839428ba0c8bb16adb","https://git.kernel.org/stable/c/e28587cc491ef0f3c51258fdc87fbc386b1d4c59"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:52:00.836172422+00:00"},"epss":{"cve":"CVE-2021-47588","score":0.00263,"percentile":0.18174,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}