high CVSS 7.8

CVE-2021-47017·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ath10k: Fix a use after free in ath10k_htc_send_bundle In ath10k_htc_send_bundle, the bundle_skb could be freed by dev_kfree_skb_any(bundle_skb). But the bundle_skb is used later by bundle_skb->len. As skb_len = bundle_skb->len, my patch replaces bundle_skb->len to skb_len after the bundle_skb was freed.

Severity
high
Software
Kernel
Fixed in
5.12.4
Published
2024-02-28

Affected versions

From: 5.12

Until: 5.12.4

Fixed in: 5.12.4

How to fix this CVE

Update your Linux kernel to version 5.12.4 or later to patch a use-after-free vulnerability in the ath10k WiFi driver's bundle transmission function. This memory safety issue could be triggered by a local attacker with limited privileges, potentially leading to privilege escalation or system crashes. Apply kernel updates immediately through your distribution's package manager.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your kernel version by running `uname -r` and verify if it falls between 5.12 and 5.12.3
  2. Step 2: Verify ath10k WiFi driver is loaded by running `lsmod | grep ath10k` - if output is empty, this vulnerability does not affect your system
  3. Step 3: Search system logs for ath10k-related crashes with `grep -i 'ath10k\|use.*after.*free' /var/log/kern.log /var/log/syslog`
  4. Step 4: After applying the kernel update, reboot and confirm new version with `uname -r` to ensure you're running 5.12.4 or later

FAQ

What is CVE-2021-47017?

A use-after-free vulnerability in the Linux kernel's ath10k WiFi driver bundle transmission code where a memory buffer is freed prematurely but then accessed again, potentially allowing local privilege escalation.

Is CVE-2021-47017 being actively exploited?

No, there is no evidence of active exploitation or publicly available exploits for this vulnerability at this time.

What versions of Kernel are affected by CVE-2021-47017?

Linux kernel versions 5.12 through 5.12.3 are vulnerable; version 5.12.4 and later contain the fix.

How do I check if my server is vulnerable to CVE-2021-47017?

Run `uname -r` to check your kernel version and `lsmod | grep ath10k` to confirm the ath10k driver is present. If your kernel version is between 5.12 and 5.12.3 and ath10k is loaded, your system is vulnerable.

Does Defensia detect CVE-2021-47017?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2021-47017 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2026-64439CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: crypto: krb5 - filter out async aead implementations at alloc krb5_aead_encrypt(), krb5_aead_decrypt() in rfc3961_simplified.c and rfc8009_encrypt(), rfc8009_decrypt() in rfc8009_aes2.c set a NULL completion callback and treat any negative return from crypto_aead_{encrypt,decrypt}() as terminal, falling through to kfree_sensitive(buffer). When the encrypt_name resolves to an async AEAD instance the request returns -EINPROGRESS, the buffer is freed while the backend's worker still holds a pointer, and the worker dereferences the freed slab on completion. KASAN report under UML+SLUB with a synthetic async aead backend bound to krb5->encrypt_name: BUG: KASAN: slab-use-after-free in t5_stub_complete+0x7d/0xc7 The helpers were written synchronously, so filter the async instances out at allocation time instead of plumbing crypto_wait_req() through every call site. Reachable via net/rxrpc/rxgk.c, fs/afs/cm_security.c and net/ceph/crypto.c on systems with an async AEAD provider bound to the krb5 enctype name.
CVE-2026-100075CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters When srpt_alloc_rw_ctxs() fails partway through a multi-buffer indirect descriptor, the unwind path destroys RDMA contexts but leaves stale n_rw_ctx and n_rdma values (and a dangling rw_ctxs pointer). Later sq_wr_avail accounting in srpt_queue_response() or srpt_write_pending() can then subtract the wrong number of send queue credits. Reset the counters and clear rw_ctxs after freeing the heap allocation before returning an error.
CVE-2026-64383CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: smb: client: fix double-free in SMB2_flush() replay SMB2_flush() keeps its response buffer bookkeeping across replay attempts. If a replayable flush response is received and the retry then fails before cifs_send_recv() stores a replacement response, flush_exit will free the stale response pointer a second time. Reinitialize resp_buftype and rsp_iov at the top of the replay loop so cleanup only acts on response state produced by the current attempt. This fixes a double-free without changing replay handling for successful requests.
CVE-2026-64385CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: smb: client: fix double-free in SMB2_ioctl() replay A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_ioctl_init() fails before the next send, cleanup retains the previous buffer type and frees that response again. Reset response bookkeeping before each attempt to prevent the stale free.
CVE-2026-64384CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: smb: client: fix change notify replay double-free A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_notify_init() fails before the next send, cleanup retains the previous buffer type and frees that response again. Reset response bookkeeping before each attempt to prevent the stale free.

References

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