CVE-2026-74714
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
A use-after-free vulnerability was found in the Linux kernel's bpf_iter_tcp_established_batch() for TCP_NEW_SYN_RECV sockets. The request_sock is published on the ehash chain before its refcount is set, and the BPF iterator uses plain sock_hold() instead of refcount_inc_not_zero(), leading to a race that overwrites the refcount and causes use-after-free.
Risk Assessment
An attacker could cause a system crash (kernel panic) or potentially escalate privileges by exploiting the race between network operations and BPF iterator reads. The vulnerability is easy to trigger in an environment with a local TCP listener and multiple threads performing connect()/close().
Recommendation
Apply the official Linux kernel patch that changes sock_hold() to refcount_inc_not_zero() and skips sockets with zero refcount. Update the system to a kernel version containing the fix.
Other vulnerabilities in Linux kernel
See all- CVE-2026-99215Unknown
In the Linux kernel power supply subsystem, a use-after-free vulnerability exists. If a power supply is unregistered while its external_power_changed() callback is still running, the driver may free data that the callback is still accessing, leading to a kernel crash (NULL pointer dereference).
- CVE-2026-99210Unknown
In the Linux kernel accel/rocket driver, rocket_probe() stores the return value of rocket_device_init() in the file-scoped rdev pointer before checking whether it is an error pointer. On failure rdev remains an ERR_PTR, and a later probe can skip initialization and dereference the error pointer when reading rdev->num_cores.
- CVE-2026-99209Unknown
In the Linux kernel drm/xe driver, xe_evict_flags() reads tbo->resource->mem_type, but a BO can reach eviction with no ttm.resource, e.g. an imported dma-buf whose resource was freed during teardown. This causes a NULL pointer dereference and a kernel fault.
- CVE-2026-99208Unknown
In the Linux kernel drm/xe/oa driver, ttm_bo_type_kernel BOs are not guaranteed to be zeroed on allocation and may contain data from previously freed pages. Since the OA buffer is mmap'able by userspace, this can expose stale kernel memory contents.
- CVE-2026-99207Unknown
In the Linux kernel's scsi: target subsystem, target_do_delayed_work() acquired delayed_cmd_lock with a plain spin_lock() without disabling interrupts, while all other acquisition sites use spin_lock_irqsave(). Since commands can now complete in interrupt context (complete_type=1 with direct_compl_supp), this can cause a deadlock when a completion arrives on the same CPU where the work item holds the lock.
- CVE-2026-99205Unknown
In the Linux kernel, a race exists in sched_change_end() with __sched_setscheduler() for queued but non-running tasks. When a task's scheduling class changes (e.g., from SCHED_OTHER to SCHED_RR), rq->next_class is not updated and the need-resched indicator is not set, causing the CPU to idle despite a runnable task being present.
- CVE-2026-99200Unknown
In the Linux kernel, the hisi_femac network driver (net: hisilicon) assigns netdev_ops only after connecting the PHY. With CONFIG_NET_SHAPER enabled, phy_attach_direct() reads uninitialized netdev_ops, causing a kernel panic from a NULL pointer dereference.
- CVE-2026-99199Unknown
In the Linux kernel, the hip04_eth network driver (net: hisilicon) calls of_phy_connect() before ndev->netdev_ops is assigned. With CONFIG_NET_SHAPER enabled, phy_attach_direct() reads uninitialized netdev_ops, causing a kernel panic from a NULL pointer dereference.
- CVE-2026-99198Unknown
In the Linux kernel, the owl_emac network driver (net: ethernet: actions) calls owl_emac_phy_init(), which connects the PHY, before netdev->netdev_ops is assigned. With CONFIG_NET_SHAPER enabled, phy_attach_direct() reads uninitialized netdev_ops, causing a kernel panic from a NULL pointer dereference.
- CVE-2026-99197Unknown
In the Linux kernel, the mv643xx_eth network driver connects the PHY before dev->netdev_ops is assigned. With CONFIG_NET_SHAPER enabled, phy_attach_direct() reads uninitialized netdev_ops, causing a kernel panic from a NULL pointer dereference.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: bpf: tcp: Fix use-after-free in bpf_iter_tcp_established_batch() reqsk_queue_hash_req() publishes a TCP_NEW_SYN_RECV request_sock onto the ehash chain, drops the bucket lock, and only afterwards sets rsk_refcnt to 3. Lockless readers such as __inet_lookup_established() handle this with refcount_inc_not_zero(), but bpf_iter_tcp_established_batch() uses plain sock_hold() while holding the bucket lock, on the assumption that the lock guarantees sk_refcnt > 0. That assumption does not hold for request_sock: CPU 0 CPU 1 ----- ----- tcp_conn_request() reqsk_queue_hash_req() inet_ehash_insert(req) spin_lock(bucket) __sk_nulls_add_node_rcu(req) // rsk_refcnt == 0 spin_unlock(bucket) bpf_iter_tcp_established_batch() spin_lock(bucket) sock_hold(req) <-- addition on 0 spin_unlock(bucket) refcount_set(&req->rsk_refcnt, 3) // clobbers saturated value which surfaces as: refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 at refcount_warn_saturate+0x48/0x90, CPU#1 Call Trace: bpf_iter_tcp_established_batch+0x14e/0x170 bpf_iter_tcp_batch+0x53/0x200 bpf_iter_tcp_seq_next+0x27/0x70 bpf_seq_read+0x107/0x410 vfs_read+0xb9/0x380 The iterator's stolen reference is lost when the publishing CPU's refcount_set() overwrites the count, leaving the socket one reference short. When the last legitimate owner drops its reference the reqsk is freed while still reachable, leading to use-after-free. This reproduces in seconds with tcp_syncookies=0, a handful of threads doing connect()/close() to a local listener while others read an iter/tcp link in a tight loop. Use refcount_inc_not_zero() and skip the socket on failure. A skipped socket is still part of the bucket, so keep counting it in expected. The reallocations are sized from expected, and a request sock whose refcount gets published while the lock is held across the last realloc must already have room. A skipped socket is counted in expected but never batched, so end_sk can be short of expected on a batch that is actually complete. Decide completeness by whether the walk left any socket behind instead. The WARN after the locked realloc checks the same, replacing an end_sk == expected check that could not hold on that path since commit cdec67a489d4 ("bpf: tcp: Make sure iter->batch always contains a full bucket snapshot"). If every matching socket in a bucket is mid-init (refcount 0), end_sk stays 0. Advance to the next bucket rather than returning a batch entry that was never filled this round.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS