CVE-2026-98255
Low risk· EPSS 8%Exploitation Probability (EPSS)
Low risk8th percentile - higher than 8% of all known CVEs
Summary
In the Linux kernel, in TCP code, old ACKs (before SND.UNA) are excluded from the fast path and directed to the slow path, where they are properly validated according to RFC5961. This prevents acceptance of old ACKs and modification of connection state before validation.
Risk Assessment
The vulnerability could allow an attacker to manipulate TCP connection state, potentially leading to unauthorized data injection or off-path attacks.
Recommendation
Update the kernel to a version with the fix that excludes old ACKs from the fast path.
Other vulnerabilities in Linux kernel
See all- CVE-2026-99216Unknown
In the Linux kernel, the Hyper-V (hv) driver incorrectly forces the VMBus connection state to DISCONNECTED before calling vmbus_disconnect(). As a result, vmbus_initiate_unload() does not unload the connection because it only acts when the state is CONNECTED, so the Hyper-V host may continue sending messages or posting VMBus interrupts.
- 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-2026-99214Unknown
In the Linux kernel, the drm/vc4 HDMI driver has an ordering issue with Packet RAM enabling. When audio is triggered by the HPD handler before video is restored, vc4_hdmi_write_infoframe() may attempt to store an infoframe while Packet RAM is disabled, causing a kernel warning (splat). The fix moves Packet RAM enable/disable into the Runtime PM hooks.
- CVE-2026-99213Unknown
In the Linux kernel vsock subsystem, the TCP_ESTABLISHED to TCP_CLOSING transition on OP_RST can race with the connect loop. Resetting a socket still present in connected_table can lead to memory corruption, including a double list add and a kernel BUG.
- CVE-2026-99212Unknown
In the Linux kernel net/rds module, rds_rdma_cm_event_handler_cmn() returns the result of rdma_resolve_route() directly to rdma_cm on RDMA_CM_EVENT_ADDR_RESOLVED. A synchronous failure causes the id ic->i_cm_id to be destroyed while RDS still owns it, leading to use of a freed id during connection shutdown.
- CVE-2026-99211Unknown
In the Linux kernel netlink subsystem, socket filters can use SKF_NET_OFF and SKF_LL_OFF to read relative to an skb's network and MAC headers. Netlink producers may reserve headroom without resetting those headers, allowing a receiving socket's filter to read data before the initialized message and disclose memory contents.
- 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.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: tcp: exclude old ACKs from tcp fast path Exclude old ACKs before SND.UNA from the tcp fast path as well as ACKs after SND.NXT. Such ACKs will fall through to the slow path, where tcp_ack() performs the appropriate validation and challenge ACK handling according to RFC5961 and Commit 3d501dd326fb1c7 ("tcp: do not accept ACK of bytes we never sent"). This prevents old ACKs from being accepted or modifying connection state as part of the fast path before appropriate ACK validation is applied. In particular, this prevents payload carried by a segment with an excessively old ACK from advancing RCV.NXT before the ACK is rejected.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

