CVE-2026-45913
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
A vulnerability has been identified in the Linux kernel related to updating the number of mdb entries in VLAN contexts. The issue arises from conditionally increasing the entry count, leading to situations where this count is not properly updated, potentially resulting in warnings during bridge operations.
Risk Assessment
Organizations may face issues with multicast management in VLAN networks, which could lead to improper functioning of applications relying on multicast and potential network performance problems.
Recommendation
It is recommended to update the Linux kernel to the latest version to remove the conditional increase of mdb entries and ensure that this count is always updated in VLAN contexts.
Other vulnerabilities in Linux kernel
See all- CVE-2026-99282Unknown
In the Linux kernel, net/sched: sch_teql contains a use-after-free vulnerability. teql_master_xmit() incorrectly treats NET_XMIT_DROP as an unconsumed packet and operates on freed memory. The issue affects configurations with VLAN interfaces and pfifo qdisc with limit 0.
- CVE-2026-99281Unknown
A flaw in the Linux kernel tun/tap mechanism allowed processes without CAP_NET_ADMIN to attach to persistent tun devices that had no owner or group set. Anyone able to open /dev/net/tun could attach to such devices and intercept or inject network traffic. The fix now requires CAP_NET_ADMIN to attach to an ownerless, groupless device.
- CVE-2026-99280Unknown
In the Linux kernel, the following vulnerability has been resolved: ksmbd: drain session procfs readers before dropping table references. Session registration failure and connection cleanup can drop the table reference while the per-session procfs entry is still accessible. If a reader holds the last remaining reference, its final put calls proc_remove() from its own callback and waits for that callback to finish. Remove the procfs entry before dropping the table reference in the registration failure path. Queue sessions removed during connection cleanup and drain their procfs readers after releasing both session locks, then return their table references. Keep the global hash node unhashed while a session is queued so a concurrent unregister cannot drop the reference again. Previous-session replacement also destroys the file table before the session is finally freed. Detach the idr under the lock used by procfs file counters, and report zero files after it has been detached. This prevents a reader from accessing the idr during or after its destruction.
- CVE-2026-99278Unknown
In the Linux kernel, the following vulnerability has been resolved: ksmbd: limit sessions on each connection. The pending setup limit only counts InProgress sessions. A client can complete authentication repeatedly and retain an unbounded number of Valid sessions on one connection. Reserve a connection slot before allocating a session and retain a connection reference while authentication is in progress. The first SMB3 channel takes over that reservation; binding to another connection reserves one slot there. Reauthentication and authentication continuation reuse the existing reservation. Return slots on allocation or insertion failure, channel removal, and final session destruction. Accept max_sessions_per_connection in reserved startup-request space and default to 64 when older tools leave it zero. Keep the request size and existing field offsets unchanged. Expose the configured limit in procfs. The existing connection limits bound the aggregate number of sessions without a separate global session allocation limit.
- CVE-2026-99259Unknown
In the Linux kernel, the soc/tegra: pmc driver has an uninitialised early_pmc->rate variable for legacy 32-bit Tegra devices. The variable is never configured and remains 0, triggering a warning in tegra_pmc_enter_suspend_mode(). The issue appeared after the PMC driver was changed to create the PMC context dynamically, updating rate only in the new context.
- CVE-2026-99258Unknown
In the Linux kernel, hv_apicid_to_vp_index() uses per-CPU hypercall input and output pages. In an SEV-SNP CoCo VM without a paravisor the output page is not allocated, so the hypervisor stores the resulting VP index into memory not allocated by the guest. The fix uses the input page for both input and output.
- CVE-2026-99257Unknown
In the Linux kernel, the shared GPIO mechanism based on platform lookup tables requires an associated struct device. An fwnode-based lookup with no associated device currently causes a NULL-pointer dereference. The fix adds a check that lets the kernel gracefully handle this situation with an error.
- CVE-2026-99256Unknown
In the Linux kernel, the dm cache module used a rw_semaphore for background_work_lock, although write locks on rw_semaphores have strict owner semantics. The locking process was not always the same as the unlocking one, triggering a warning with CONFIG_DEBUG_RWSEMS during suspend/resume of a cache device. The fix replaces the rw_semaphore with a spinlock and a wait queue.
- CVE-2026-99251Unknown
In the Linux kernel, init_vp_index() contains a retry loop that strips CPUs from a node if they are already in the allocated cpumask or outside the HK_TYPE_MANAGED_IRQ housekeeping cpumask. If the housekeeping cpumask contains no CPU in that node, the loop becomes infinite. The fix skips NUMA nodes with no housekeeping CPU and aborts early when no online housekeeping CPUs exist.
- CVE-2026-99250Unknown
In the Linux kernel, the NBCON console printing kthreads are started very early during boot via early_initcall(). Asynchronously enabling/disabling interrupts during early boot may interfere with early SMP setup on some hardware platforms, causing hangs. The fix postpones kthread startup until after all arch initcalls have completed.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: net: bridge: mcast: always update mdb_n_entries for vlan contexts syzbot triggered a warning[1] about the number of mdb entries in a context. It turned out that there are multiple ways to trigger that warning today (some got added during the years), the root cause of the problem is that the increase is done conditionally, and over the years these different conditions increased so there were new ways to trigger the warning, that is to do a decrease which wasn't paired with a previous increase. For example one way to trigger it is with flush: $ ip l add br0 up type bridge vlan_filtering 1 mcast_snooping 1 $ ip l add dumdum up master br0 type dummy $ bridge mdb add dev br0 port dumdum grp 239.0.0.1 permanent vid 1 $ ip link set dev br0 down $ ip link set dev br0 type bridge mcast_vlan_snooping 1 ^^^^ this will enable snooping, but will not update mdb_n_entries because in __br_multicast_enable_port_ctx() we check !netif_running $ bridge mdb flush dev br0 ^^^ this will trigger the warning because it will delete the pg which we added above, which will try to decrease mdb_n_entries Fix the problem by removing the conditional increase and always keep the count up-to-date while the vlan exists. In order to do that we have to first initialize it on port-vlan context creation, and then always increase or decrease the value regardless of mcast options. To keep the current behaviour we have to enforce the mdb limit only if the context is port's or if the port-vlan's mcast snooping is enabled. [1] ------------[ cut here ]------------ n == 0 WARNING: net/bridge/br_multicast.c:718 at br_multicast_port_ngroups_dec_one net/bridge/br_multicast.c:718 [inline], CPU#0: syz.4.4607/22043 WARNING: net/bridge/br_multicast.c:718 at br_multicast_port_ngroups_dec net/bridge/br_multicast.c:771 [inline], CPU#0: syz.4.4607/22043 WARNING: net/bridge/br_multicast.c:718 at br_multicast_del_pg+0x1bbe/0x1e20 net/bridge/br_multicast.c:825, CPU#0: syz.4.4607/22043 Modules linked in: CPU: 0 UID: 0 PID: 22043 Comm: syz.4.4607 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 RIP: 0010:br_multicast_port_ngroups_dec_one net/bridge/br_multicast.c:718 [inline] RIP: 0010:br_multicast_port_ngroups_dec net/bridge/br_multicast.c:771 [inline] RIP: 0010:br_multicast_del_pg+0x1bbe/0x1e20 net/bridge/br_multicast.c:825 Code: 41 5f 5d e9 04 7a 48 f7 e8 3f 73 5c f7 90 0f 0b 90 e9 cf fd ff ff e8 31 73 5c f7 90 0f 0b 90 e9 16 fd ff ff e8 23 73 5c f7 90 <0f> 0b 90 e9 60 fd ff ff e8 15 73 5c f7 eb 05 e8 0e 73 5c f7 48 8b RSP: 0018:ffffc9000c207220 EFLAGS: 00010293 RAX: ffffffff8a68042d RBX: ffff88807c6f1800 RCX: ffff888066e90000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffff888066e90000 R09: 000000000000000c R10: 000000000000000c R11: 0000000000000000 R12: ffff8880303ef800 R13: dffffc0000000000 R14: ffff888050eb11c4 R15: 1ffff1100a1d6238 FS: 00007fa45921b6c0(0000) GS:ffff8881256f5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa4591f9ff8 CR3: 0000000081df2000 CR4: 00000000003526f0 Call Trace: <TASK> br_mdb_flush_pgs net/bridge/br_mdb.c:1525 [inline] br_mdb_flush net/bridge/br_mdb.c:1544 [inline] br_mdb_del_bulk+0x5e2/0xb20 net/bridge/br_mdb.c:1561 rtnl_mdb_del+0x48a/0x640 net/core/rtnetlink.c:-1 rtnetlink_rcv_msg+0x77e/0xbe0 net/core/rtnetlink.c:6967 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa68/0xad0 net/socket.c:2592 ___sys_sendmsg+0x2a5/0x360 net/socke ---truncated---
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

