cbcvebase.
CVE-2026-23276
published 2026-03-20

CVE-2026-23276: In the Linux kernel, the following vulnerability has been resolved: net: add xmit recursion limit to tunnel xmit functions Tunnel xmit functions…

PriorityP422medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.13%
2.9th percentile
In the Linux kernel, the following vulnerability has been resolved: net: add xmit recursion limit to tunnel xmit functions Tunnel xmit functions (iptunnel_xmit, ip6tunnel_xmit) lack their own recursion limit. When a bond device in broadcast mode has GRE tap interfaces as slaves, and those GRE tunnels route back through the bond, multicast/broadcast traffic triggers infinite recursion between bond_xmit_broadcast() and ip_tunnel_xmit()/ip6_tnl_xmit(), causing kernel stack overflow. The existing XMIT_RECURSION_LIMIT (8) in the no-qdisc path is not sufficient because tunnel recursion involves route lookups and full IP output, consuming much more stack per level. Use a lower limit of 4 (IP_TUNNEL_RECURSION_LIMIT) to prevent overflow. Add recursion detection using dev_xmit_recursion helpers directly in iptunnel_xmit() and ip6tunnel_xmit() to cover all IPv4/IPv6 tunnel paths including UDP encapsulated tunnels (VXLAN, Geneve, etc.). Move dev_xmit_recursion helpers from net/core/dev.h to public header include/linux/netdevice.h so they can be used by tunnel code. BUG: KASAN: stack-out-of-bounds in blake2s.constprop.0+0xe7/0x160 Write of size 32 at addr ffff88810033fed0 by task kworker/0:1/11 Workqueue: mld mld_ifc_work Call Trace: __build_flow_key.constprop.0 (net/ipv4/route.c:515) ip_rt_update_pmtu (net/ipv4/route.c:1073) iptunnel_xmit (net/ipv4/ip_tunnel_core.c:84) ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847) gre_tap_xmit (net/ipv4/ip_gre.c:779) dev_hard_start_xmit (net/core/dev.c:3887) sch_direct_xmit (net/sched/sch_generic.c:347) __dev_queue_xmit (net/core/dev.c:4802) bond_dev_queue_xmit (drivers/net/bonding/bond_main.c:312) bond_xmit_broadcast (drivers/net/bonding/bond_main.c:5279) bond_start_xmit (drivers/net/bonding/bond_main.c:5530) dev_hard_start_xmit (net/core/dev.c:3887) __dev_queue_xmit (net/core/dev.c:4841) ip_finish_output2 (net/ipv4/ip_output.c:237) ip_output (net/ipv4/ip_output.c:438) iptunnel_xmit (net/ipv4/ip_tunnel_core.c:86) gre_tap_xmit (net/ipv4/ip_g

Affected

41 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.19.10-1 (forky)linux 6.19.10-1 (forky)
linuxlinux
linuxlinux
linuxlinux>= 2.6.35.9 < 2.6.362.6.36
linuxlinux>= 745e20f1b626b1be4b100af5d4bf7b3439392f8f < 834c4f645726a25fd71ea50cdfb5c135f8f95d85834c4f645726a25fd71ea50cdfb5c135f8f95d85
linuxlinux>= 745e20f1b626b1be4b100af5d4bf7b3439392f8f < 8a57deeb256069f262957d8012418559ff66c3858a57deeb256069f262957d8012418559ff66c385
linuxlinux>= 745e20f1b626b1be4b100af5d4bf7b3439392f8f < b56b8d19bd05e2a8338385c770bc2b60590bc81eb56b8d19bd05e2a8338385c770bc2b60590bc81e
linuxlinux>= 745e20f1b626b1be4b100af5d4bf7b3439392f8f < 6f1a9140ecda3baba3d945b9a6155af4268aafc46f1a9140ecda3baba3d945b9a6155af4268aafc4
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.19.10-16.19.10-1
linuxlinux_kernel>= 2.6.35.9 < 2.6.362.6.36
linuxlinux_kernel>= 2.6.37 < 6.12.786.12.78
linuxlinux_kernel>= 2.6.37 < 6.12.786.12.78
linuxlinux_kernel>= 6.13 < 6.18.196.18.19
linuxlinux_kernel>= 6.13.0 < 6.18.196.18.19
linuxlinux_kernel>= 6.19 < 6.19.96.19.9
linuxlinux_kernel>= 6.19.0 < 6.19.96.19.9
msrcazl3_kernel_6.6.126.1-1_on_azure_linux_3.0
ubuntulinux
ubuntulinux-aws
ubuntulinux-azure
ubuntulinux-azure-6.8
ubuntulinux-azure-fde
ubuntulinux-azure-fde-6.8
ubuntulinux-azure-fips

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vendor_msrc5.5MEDIUM
vendor_redhat5.5MEDIUM
vendor_ubuntu2.0LOW
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