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

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于teql_master_xmit未在发送前更新skb->dev指向从设备，可能导致空指针取消引用。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.12% · P2

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 039f50629b7f860f36644ed1f34b27da9aa62f43< 383493b9940e3d1b5517424081b3e072e20ec43c affected
039f50629b7f860f36644ed1f34b27da9aa62f43< 6b1f563d670162e188a0f2aec39c24b67b106e17 affected
039f50629b7f860f36644ed1f34b27da9aa62f43< 57c153249143333bbf4ecf927bdf8aa2696ee397 affected
039f50629b7f860f36644ed1f34b27da9aa62f43< 59b06d8b9bdb6b64b3c534c18da68bce5ccd31be affected
039f50629b7f860f36644ed1f34b27da9aa62f43< 81a43e8005366f16e629d8c95dfe05beaa8d36a7 affected
039f50629b7f860f36644ed1f34b27da9aa62f43< 0bad9c86edd22dec4df83c2b29872d66fd8a2ff4 affected
039f50629b7f860f36644ed1f34b27da9aa62f43< 21ea283c2750c8307aa35ee832b0951cc993c27d affected
039f50629b7f860f36644ed1f34b27da9aa62f43< 0cc0c2e661af418bbf7074179ea5cfffc0a5c466 affected
… +10 more rows
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I. Basic Information for CVE-2026-23277

Vulnerability Information
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Vulnerability Title
net/sched: teql: fix NULL pointer dereference in iptunnel_xmit on TEQL slave xmit
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于teql_master_xmit未在发送前更新skb->dev指向从设备，可能导致空指针取消引用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 039f50629b7f860f36644ed1f34b27da9aa62f43 ~ 383493b9940e3d1b5517424081b3e072e20ec43c -
Linux Linux 4.5 -

II. Public POCs for CVE-2026-23277

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III. Intelligence Information for CVE-2026-23277

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Patches & Fixes for CVE-2026-23277 (6)

Same Patch Batch · Linux · 2026-03-20 · 8 CVEs total

CVE-2026-23278 7.8 HIGH netfilter: nf_tables: always walk all pending catchall elements
CVE-2026-23275 7.8 HIGH io_uring: ensure ctx->rings is stable for task work flags manipulation
CVE-2026-23274 7.8 HIGH netfilter: xt_IDLETIMER: reject rev0 reuse of ALARM timer labels
CVE-2026-23273 7.8 HIGH macvlan: observe an RCU grace period in macvlan_common_newlink() error path
CVE-2026-23272 7.8 HIGH netfilter: nf_tables: unconditionally bump set->nelems before insertion
CVE-2026-23271 7.8 HIGH perf: Fix __perf_event_overflow() vs perf_remove_from_context() race
CVE-2026-23276 net: add xmit recursion limit to tunnel xmit functions

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23277

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