Linux KernelOperating system · Linux
CVE-2021-47395
A fix is available.
Upgrade to 4.9.285 / 4.14.249 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click
Patch available
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn the Linux kernel, the following vulnerability has been resolved: mac80211: limit injected vht mcs/nss in ieee80211_parse_tx_radiotap Limit max values for vht mcs and nss in ieee80211_parse_tx_radiotap routine in order to fix the following warning reported by syzbot: WARNING: CPU: 0 PID: 10717 at include/net/mac80211.h:989 ieee80211_rate_set_vht include/net/mac80211.h:989 [inline] WARNING: CPU: 0 PID: 10717 at include/net/mac80211.h:989 ieee80211_parse_tx_radiotap+0x101e/0x12d0 net/mac80211/tx.c:2244 Modules linked in: CPU: 0 PID: 10717 Comm: syz-executor.5 Not tainted 5.14.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:ieee80211_rate_set_vht include/net/mac80211.h:989 [inline] RIP: 0010:ieee80211_parse_tx_radiotap+0x101e/0x12d0 net/mac80211/tx.c:2244 RSP: 0018:ffffc9000186f3e8 EFLAGS: 00010216 RAX: 0000000000000618 RBX: ffff88804ef76500 RCX: ffffc900143a5000 RDX: 0000000000040000 RSI: ffffffff888f478e RDI: 0000000000000003 RBP: 00000000ffffffff R08: 0000000000000000 R09: 0000000000000100 R10: ffffffff888f46f9 R11: 0000000000000000 R12: 00000000fffffff8 R13: ffff88804ef7653c R14: 0000000000000001 R15: 0000000000000004 FS: 00007fbf5718f700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2de23000 CR3: 000000006a671000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Call Trace: ieee80211_monitor_select_queue+0xa6/0x250 net/mac80211/iface.c:740 netdev_core_pick_tx+0x169/0x2e0 net/core/dev.c:4089 __dev_queue_xmit+0x6f9/0x3710 net/core/dev.c:4165 __bpf_tx_skb net/core/filter.c:2114 [inline] __bpf_redirect_no_mac net/core/filter.c:2139 [inline] __bpf_redirect+0x5ba/0xd20 net/core/filter.c:2162 ____bpf_clone_redirect net/core/filter.c:2429 [inline] bpf_clone_redirect+0x2ae/0x420 net/core/filter.c:2401 bpf_prog_eeb6f53a69e5c6a2+0x59/0x234 bpf_dispatcher_nop_func include/linux/bpf.h:717 [inline] __bpf_prog_run include/linux/filter.h:624 [inline] bpf_prog_run include/linux/filter.h:631 [inline] bpf_test_run+0x381/0xa30 net/bpf/test_run.c:119 bpf_prog_test_run_skb+0xb84/0x1ee0 net/bpf/test_run.c:663 bpf_prog_test_run kernel/bpf/syscall.c:3307 [inline] __sys_bpf+0x2137/0x5df0 kernel/bpf/syscall.c:4605 __do_sys_bpf kernel/bpf/syscall.c:4691 [inline] __se_sys_bpf kernel/bpf/syscall.c:4689 [inline] __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4689 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665f9
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysisA detailed technical summary for this CVE is being prepared.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Linux KernelOperating system
Affected:
>= 4.7, < 4.9.285>= 4.10, < 4.14.249>= 4.15, < 4.19.209>= 4.20, < 5.4.151>= 5.5, < 5.10.71>= 5.11, < 5.14.10= 5.15CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped
Upgrade available
Upgrade to 4.9.285 / 4.14.249 / 4.19.209 or later
Fixed in
4.9.2854.14.2494.19.209
Vendor patch
git.kernel.org →
Recommended fix
High confidence
Upgrade to kernel >=4.9.285 (4.9.x), >=4.14.249 (4.14.x), >=4.19.209 (4.19.x), or >=5.4.151 (5.4.x) depending on your branch
- Identify the currently running kernel version using `uname -r` or `cat /proc/version`
- Determine which version branch your kernel belongs to (4.7-4.9.x, 4.10-4.14.x, 4.15-4.19.x, or 4.20-5.4.x)
- Upgrade to a patched kernel version appropriate for your branch: for 4.9.x line upgrade to >=4.9.285, for 4.14.x line upgrade to >=4.14.249, for 4.19.x line upgrade to >=4.19.209, or for 5.4.x line upgrade to >=5.4.151
- Reboot the system to load the patched kernel
- Verify the fix is applied by checking the kernel version and confirming the vulnerability is resolved
Caveat Minor - this is a security hardening fix that adds input validation; no functional breaking changes expected for typical use cases
Generated from the published advisory — verify against the referenced sources before acting.
We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600.
Get the upgrade done
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Free · runs locally
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-47395 in production — separate from our analysis above.
Know something about CVE-2021-47395?
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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What belongs here
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