Medium 5.5Published Mar 20, 2026

CVE-2026-23277net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit

Updated under an hour ago (Oct 27, 2026, 8:50 PM ET)

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In the Linux kernel, the following vulnerability has been resolved: net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit teql_master_xmit() calls netdev_start_xmit(skb, slave) to transmit through slave devices, but does not update skb->dev to the slave device beforehand. When a gretap tunnel is a TEQL slave, the transmit path reaches iptunnel_xmit() which saves dev = skb->dev (still pointing to teql0 master) and later calls iptunnel_xmit_stats(dev, pkt_len). This function does: get_cpu_ptr(dev->tstats) Since teql_master_setup() does not set dev->pcpu_stat_type to NETDEV_PCPU_STAT_TSTATS, the core network stack never allocates tstats for teql0, so dev->tstats is NULL. get_cpu_ptr(NULL) computes NULL + __per_cpu_offset[cpu], resulting in a page fault. BUG: unable to handle page fault for address: ffff8880e6659018 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 68bc067 P4D 68bc067 PUD 0 Oops: Oops: 0002 [#1] SMP KASAN PTI RIP: 0010:iptunnel_xmit (./include/net/ip_tunnels.h:664 net/ipv4/ip_tunnel_core.c:89) Call Trace: <TASK> ip_tunnel_xmit (net/ipv4/ip_tunnel.c:847) __gre_xmit (net/ipv4/ip_gre.c:478) gre_tap_xmit (net/ipv4/ip_gre.c:779) teql_master_xmit (net/sched/sch_teql.c:319) 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) neigh_direct_output (net/core/neighbour.c:1660) ip_finish_output2 (net/ipv4/ip_output.c:237) __ip_finish_output.part.0 (net/ipv4/ip_output.c:315) ip_mc_output (net/ipv4/ip_output.c:369) ip_send_skb (net/ipv4/ip_output.c:1508) udp_send_skb (net/ipv4/udp.c:1195) udp_sendmsg (net/ipv4/udp.c:1485) inet_sendmsg (net/ipv4/af_inet.c:859) __sys_sendto (net/socket.c:2206) Fix this by setting skb->dev = slave before calling netdev_start_xmit(), so that tunnel xmit functions see the correct slave device with properly allocated tstats.

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 039f50629b7f860f36644ed1f34b27da9aa62f43 before 383493b9940e3d1b5517424081b3e072e20ec43c; 039f50629b7f860f36644ed1f34b27da9aa62f43 builds before 6b1f563d670162e188a0f2aec39c24b67b106e17; from 039f50629b7f860f36644ed1f34b27da9aa62f43 before 57c153249143333bbf4ecf927bdf8aa2696ee397; from 039f50629b7f860f36644ed1f34b27da9aa62f43 before 59b06d8b9bdb6b64b3c534c18da68bce5ccd31be; from 039f50629b7f860f36644ed1f34b27da9aa62f43 before 81a43e8005366f16e629d8c95dfe05beaa8d36a7; 039f50629b7f860f36644ed1f34b27da9aa62f43 builds before 0bad9c86edd22dec4df83c2b29872d66fd8a2ff4; 039f50629b7f860f36644ed1f34b27da9aa62f43 builds before 21ea283c2750c8307aa35ee832b0951cc993c27d; 039f50629b7f860f36644ed1f34b27da9aa62f43 builds before 0cc0c2e661af418bbf7074179ea5cfffc0a5c466	CNA record
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name)	all versions	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
linux linux_kernel linux:linux_kernel	from 4.5 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.78; from 6.13 before 6.18.19; from 6.19 before 6.19.9; 7.0; and 2 more ranges	NVD

References

References

https://git.kernel.org/stable/c/383493b9940e3d1b5517424081b3e072e20ec43c	patch
https://git.kernel.org/stable/c/6b1f563d670162e188a0f2aec39c24b67b106e17	patch
https://git.kernel.org/stable/c/57c153249143333bbf4ecf927bdf8aa2696ee397	patch
https://git.kernel.org/stable/c/59b06d8b9bdb6b64b3c534c18da68bce5ccd31be	patch
https://git.kernel.org/stable/c/81a43e8005366f16e629d8c95dfe05beaa8d36a7	patch
https://git.kernel.org/stable/c/0bad9c86edd22dec4df83c2b29872d66fd8a2ff4	patch
https://git.kernel.org/stable/c/21ea283c2750c8307aa35ee832b0951cc993c27d	patch
https://git.kernel.org/stable/c/0cc0c2e661af418bbf7074179ea5cfffc0a5c466	patch
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
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The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.