CVE-2026-98377
UnknownSummary
In the Linux kernel, __vlan_insert_inner_tag() does not require the MAC header to be present before rewriting it. When a very short frame is sent through an IFF_TUN device, subsequent VLAN push operations can pull uninitialized slab bytes into the frame, leaking kernel memory.
Risk Assessment
Uninitialized kernel memory may leak to the network, potentially exposing sensitive data or aiding in bypassing security mechanisms such as ASLR.
Recommendation
Update the Linux kernel to a version with the fix requiring the MAC header to be present in __vlan_insert_inner_tag(). Restrict the ability to create IFF_TUN devices and send raw AF_PACKET frames to trusted users.
Other vulnerabilities in Linux kernel
See all- CVE-2026-98384Unknown
In the Linux kernel, bpf_sock_destroy() reads sk_protocol from the wrong structure, causing an out-of-bounds read. The issue affects TIME_WAIT and request sockets passed by the TCP iterator. The fix restricts the sk_protocol check to full sockets only.
- CVE-2026-98383Unknown
In the Linux kernel, LWT_SEG6LOCAL programs can invalidate the cached SRH and then call bpf_skb_pull_data(), leading to a dangling pointer and use-after-free. The fix disallows bpf_skb_pull_data() for LWT_SEG6LOCAL programs.
- CVE-2026-98382Unknown
In the Linux kernel, the BPF device matching mechanism has a flaw that allows a program bound to one device to run on another, leading to memory corruption. The fix restricts non-offloaded programs to exact netdev matches.
- CVE-2026-98381Unknown
In the Linux kernel, during veth channel resize, XDP program pointers are not cleared for removed RX queues. This can lead to running a freed program after a later channel increase, causing a system crash.
- CVE-2026-98380Unknown
In the Linux kernel's net/sched subsystem, a vulnerability exists where tcf_action_delete() fails to check if the IDR lookup result is an error pointer (ERR_PTR). An attacker can exploit a race to replace an action with an error pointer, leading to a null-pointer dereference and kernel panic.
- CVE-2026-98379Unknown
A vulnerability in the Linux kernel's netfilter ip6t_rpfilter module was found, where ip6_route_lookup() can return a route without an inet6_dev (NULL pointer). An unprivileged user can trigger this state by lowering an external interface's MTU below IPV6_MIN_MTU, leading to a NULL pointer dereference and kernel panic.
- CVE-2026-98378Unknown
In the Linux kernel, a vulnerability exists in the BPF link iterator. bpf_link_prime() inserts a link into link_idr before the ID is published, and the link iterator takes a reference without checking whether the link is settled (ID zero). If anon_inode_getfile() fails, the iterator is left with a dangling reference and a subsequent bpf_link_put() accesses freed memory (use-after-free).
- CVE-2026-98376Unknown
In the Linux kernel, the metadata comparison for percpu array BPF maps used as inner maps does not check max_entries. Replacing an inner map with a smaller one bypasses validation, and the index_mask inlined by the JIT can cause an out-of-bounds access to the pptrs[] array.
- CVE-2026-98375Unknown
In the Linux kernel, the xen/netfront driver does not validate the length of the first RX slot against ETH_HLEN before calling eth_type_trans(). If the first slot is shorter than an Ethernet header, a BUG() may occur in __skb_pull() or the header may be read past the end of the data.
- CVE-2026-98374Unknown
In the Linux kernel, a use-after-free vulnerability exists in tcp_send_synack() involving retransmit_skb_hint. When tcp_send_synack() replaces the cloned SYN skb at the head of the retransmit queue with a copy, it frees the original but tp->retransmit_skb_hint still points to the freed object, which can be exploited by an unprivileged TFO client to trigger a use-after-free.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: vlan: require the MAC header to be present in __vlan_insert_inner_tag() __vlan_insert_inner_tag() only guarantees head room via skb_cow_head(), never that mac_len bytes of MAC header are present. Its ETH_HLEN wrappers - __vlan_insert_tag() under skb_vlan_push(), and vlan_insert_tag() under validate_xmit_vlan() on the generic transmit path - therefore rewrite the first 16 bytes at skb->data: a 12-byte memmove plus two 2-byte stores at +12 and +14. No caller supplies the bound, while the pop helpers use skb_ensure_writable()/pskb_may_pull(). An IFF_TUN device has hard_header_len == 0, so packet_snd() accepts a one-byte AF_PACKET/SOCK_RAW frame. The first vlan push only sets a hwaccel tag; the next - clsact "action vlan push" or bpf_skb_vlan_push() - enters the helper with skb->len still 1. The head comes from skbuff_small_head without __GFP_ZERO, so each push drags bytes from beyond skb->tail into the frame. After three the one-byte send leaves as 13 bytes carrying 11 bytes of uninitialised slab: 0000: 5a b3 62 12 80 88 ff ff 00 b3 62 12 81 `------------------------------' only 0x5a was sent; the rest is slab, here the top 56 bits of a linear-map address Require the MAC header the helper rewrites to be present, so such a frame is dropped rather than transmitted.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

