critical CVSS 9.8

CVE-2026-64113·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: ixgbevf: fix use-after-free in VEPA multicast source pruning ixgbevf_clean_rx_irq() prunes frames whose source MAC matches the VF's own address (VEPA multicast workaround) by freeing the skb and continuing to the next descriptor: dev_kfree_skb_irq(skb); continue; The skb pointer is declared outside the while loop and persists across iterations. Because the continue skips the "skb = NULL" reset at the bottom of the loop, the next iteration enters the "else if (skb)" path and calls ixgbevf_add_rx_frag() on the freed skb, dereferencing skb_shinfo(skb)->nr_frags - a use-after-free in NAPI softirq context. The sibling driver iavf already handles this correctly by nulling the pointer before continuing. Apply the same pattern here. I do not have ixgbevf hardware; the bug was found by static analysis (scan_drop_continue_loops.py + semgrep drop_continue_in_loop, multi-tool corroboration with the highest score in the scan). The UAF was confirmed under KASAN by loading a test module that reproduces the exact code pattern (alloc skb, kfree_skb, then read skb_shinfo(skb)->nr_frags): BUG: KASAN: slab-use-after-free in ixgbevf_uaf_test_init+0x100/0x1000 Read of size 8 at addr 000000006163ae78 by task insmod/30 freed 208-byte region [000000006163adc0, 000000006163ae90) QEMU emulates igb (82576) but not ixgbe (82599), and the igbvf VF driver does not include the VEPA source pruning path, so a full end-to-end reproduction with emulated hardware was not possible.

Severity
critical
Software
Kernel
Fixed in
7.0.11
Published

Affected versions

From: 6.19

Until: 7.0.11

Fixed in: 7.0.11

How to fix this CVE

Update your Linux kernel to version 7.0.11 or later to patch a use-after-free vulnerability in the ixgbevf driver's VEPA multicast handling. This flaw allows kernel memory corruption in network packet processing that can lead to system instability or potential privilege escalation. Apply the patch immediately if you are running ixgbevf-dependent Intel 82599 virtual function hardware.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Check kernel version: uname -r — compare output against vulnerable range 6.19 to 7.0.10
  2. Verify ixgbevf driver is loaded: lsmod | grep ixgbevf — if present, system is potentially vulnerable
  3. Check dmesg for KASAN errors: dmesg | grep -i 'use-after-free\|ixgbevf' — exploitation attempts may trigger kernel memory warnings
  4. Confirm patch applied: grep 'ixgbevf_clean_rx_irq' /boot/config-$(uname -r) && uname -r | grep -E '^7\.0\.1[1-9]|^7\.[1-9]' — patched kernels will show version 7.0.11 or higher

FAQ

What is CVE-2026-64113?

This is a use-after-free vulnerability in the Linux kernel's ixgbevf driver where freed network packet buffers are incorrectly reused during VEPA multicast frame filtering, potentially causing kernel memory corruption.

Is CVE-2026-64113 being actively exploited?

No—CISA has not listed this CVE in the Known Exploited Vulnerabilities catalog, and no public exploit code is currently available. The vulnerability was discovered through static code analysis rather than real-world attacks.

What versions of Kernel are affected by CVE-2026-64113?

Linux kernel versions 6.19 through 7.0.10 are vulnerable. Version 7.0.11 and later include the fix.

How do I check if my server is vulnerable to CVE-2026-64113?

Run 'uname -r' and verify your kernel version is in the range 6.19–7.0.10. Additionally, check 'lsmod | grep ixgbevf' to confirm the vulnerable driver is loaded; if ixgbevf is not present, your system is not affected.

Does Defensia detect CVE-2026-64113?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Linux kernel is installed on a monitored server, CVE-2026-64113 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2026-63795CVSS 10In the Linux kernel, the following vulnerability has been resolved: 9p: avoid putting oldfid in p9_client_walk() error path When p9_client_walk() is called with clone set to false, fid aliases oldfid. If the walk subsequently fails after the request has been sent, the error path jumps to clunk_fid, which currently calls p9_fid_put(fid) unconditionally. This drops a reference to oldfid even though ownership of oldfid remains with the caller. If this is the last reference, oldfid can be clunked and destroyed while the caller still expects it to be valid. A later use or put of oldfid can then trigger a use-after-free or refcount underflow. Fix this by only putting fid in the clunk_fid error path when it does not alias oldfid, matching the existing guard in the error path below. This can be triggered when a multi-component walk is split into multiple p9_client_walk() calls and a later non-cloning walk fails. A reproducer and refcount warning logs are available on request.
CVE-2026-52955CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: libceph: Fix potential out-of-bounds access in crush_decode() A message of type CEPH_MSG_OSD_MAP containing a crush map with at least one bucket has two fields holding the bucket algorithm. If the values in these two fields differ, an out-of-bounds access can occur. This is the case because the first algorithm field (alg) is used to allocate the correct amount of memory for a bucket of this type, while the second algorithm field inside the bucket (b->alg) is used in the subsequent processing. This patch fixes the issue by adding a check that compares alg and b->alg and aborts the processing in case they differ. Furthermore, b->alg is set to 0 in this case, because the destruction of the crush map also uses this field to determine the bucket type, which can again result in an out-of-bounds access when trying to free the memory pointed to by the fields of the bucket. To correctly free the memory allocated for the bucket in such a case, the corresponding call to kfree is moved from the algorithm-specific crush_destroy_bucket functions to the generic crush_destroy_bucket().
CVE-2026-53384CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: serial: 8250_dw: unregister 8250 port if clk_notifier_register() fails dw8250_probe() registers the 8250 port via serial8250_register_8250_port() and then, if the device has a clock, registers a clock notifier. If clk_notifier_register() fails, probe returns the error but leaves the 8250 port registered. The matching serial8250_unregister_port() lives in dw8250_remove(), which is not called when probe fails, so the port slot stays occupied until the device is rebound or the system is rebooted. The devm-allocated driver data is freed while the port still references it (via the saved private_data and serial_in/serial_out callbacks), so any access to that port slot before a rebind is a use-after-free hazard. Unregister the port on the clk_notifier_register() error path.
CVE-2026-53399CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: nfsd: release layout stid on setlease failure nfs4_alloc_stid() publishes the new stid into cl->cl_stateids via idr_alloc_cyclic() under cl_lock before returning to nfsd4_alloc_layout_stateid(). When nfsd4_layout_setlease() then fails, the error path frees the layout stateid directly with kmem_cache_free() without ever calling idr_remove(), leaving the IDR slot pointing at freed slab memory. Any subsequent IDR walker (states_show, client teardown) dereferences the dangling pointer. The correct teardown for an IDR-published stid is nfs4_put_stid(), which removes the IDR slot under cl_lock, dispatches sc_free (nfsd4_free_layout_stateid) to release ls->ls_file via nfsd4_close_layout(), and drops the nfs4_file reference in its tail. A second issue blocks that switch: nfsd4_free_layout_stateid() unconditionally inspects ls->ls_fence_work via delayed_work_pending() under ls_lock, but INIT_DELAYED_WORK(&ls->ls_fence_work, ...) currently runs only after the setlease call. On the setlease-failure path the destructor would touch an uninitialized delayed_work. nfsd4_alloc_layout_stateid() nfs4_alloc_stid() /* idr_alloc_cyclic under cl_lock */ nfsd4_layout_setlease() /* fails */ nfs4_put_stid() nfsd4_free_layout_stateid() delayed_work_pending(&ls->ls_fence_work) /* needs INIT */ nfsd4_close_layout() /* nfsd_file_put(ls->ls_file) */ put_nfs4_file() Fix by hoisting the ls_fenced / ls_fence_delay / INIT_DELAYED_WORK initialization above the nfsd4_layout_setlease() call, and replace the manual nfsd_file_put + put_nfs4_file + kmem_cache_free cleanup with a single nfs4_put_stid(stp).
CVE-2026-53260CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req(). syzbot reported a weird reqsk->rsk_refcnt underflow in __inet_csk_reqsk_queue_drop(). The captured reqsk_put() in __inet_csk_reqsk_queue_drop() is called only when it successfully removes reqsk from ehash. Moreover, reqsk_timer_handler() calls another reqsk_put() after that. This indicates that the reqsk was missing both refcnts for ehash and the timer itself. Since all the syzbot reports had PREEMPT_RT enabled, the only possible scenario is that reqsk_queue_hash_req() is preempted after mod_timer() and before refcount_set(), and then the timer triggered after 1s aborts the reqsk due to its listener's close(). Let's wrap mod_timer() and refcount_set() with preempt_disable_nested() and preempt_enable_nested(). Note that inet_ehash_insert() holds the normal spin_lock() (mutex in PREEMPT_RT), so it must be called outside of preempt_disable_nested(), but this is fine. The lookup path just ignores 0 sk_refcnt entries in ehash and tries to create another reqsk, but this will fail at inet_ehash_insert(). [0]: refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: ktimers/0/16 Modules linked in: CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 RIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28 Code: e4 7d d1 0a 67 48 0f b9 3a eb 4a e8 38 3d 23 fd 48 8d 3d e1 7d d1 0a 67 48 0f b9 3a eb 37 e8 25 3d 23 fd 48 8d 3d de 7d d1 0a <67> 48 0f b9 3a eb 24 e8 12 3d 23 fd 48 8d 3d db 7d d1 0a 67 48 0f RSP: 0000:ffffc90000157948 EFLAGS: 00010246 RAX: ffffffff84a1301b RBX: 0000000000000003 RCX: ffff88801ca98000 RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffffff8f72ae00 RBP: ffffffff99ae3b01 R08: ffff88801ca98000 R09: 0000000000000005 R10: 0000000000000100 R11: 0000000000000004 R12: ffff8880425ef568 R13: ffff8880425ef4f8 R14: ffff8880425ef578 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888126386000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7b46710e9c CR3: 000000000dbb6000 CR4: 00000000003526f0 Call Trace: <TASK> __refcount_sub_and_test include/linux/refcount.h:400 [inline] __refcount_dec_and_test include/linux/refcount.h:432 [inline] refcount_dec_and_test include/linux/refcount.h:450 [inline] reqsk_put include/net/request_sock.h:136 [inline] __inet_csk_reqsk_queue_drop+0x3ce/0x440 net/ipv4/inet_connection_sock.c:1007 reqsk_timer_handler+0x651/0xdf0 net/ipv4/inet_connection_sock.c:1137 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748 expire_timers kernel/time/timer.c:1799 [inline] __run_timers kernel/time/timer.c:2374 [inline] __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2386 run_timer_base kernel/time/timer.c:2395 [inline] run_timer_softirq+0x67/0x170 kernel/time/timer.c:2403 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] run_ktimerd+0x69/0x100 kernel/softirq.c:1151 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>

References

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