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CVE-2026-98401— net: iptunnel: fix stale transport header during tunnel decapsulation

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.

以下是该漏洞描述信息的中文翻译： 在 Linux 内核中，已解决以下漏洞： 网络：iptunnel：修复隧道解封装期间传输头（transport header）过时的问题 Syzbot 报告称，在 中发生崩溃，其原因是在隧道解封装后， 偏移量过时（stale）。 该问题在 commit （"net: pull headers in qdisc_pkt_len_segs_init()"）引入 qdisc 读取传输头之前完全潜伏。崩溃需要以下四个条件同时满足： 1. 传入的数据包是封装的并携带 GSO（通用分段卸载）元

AI Predicted 6.5 Difficulty: Moderate EPSS 0.21% · P10

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 8c3d4dfcecf7670c1d752f1ae74b21b2af5feac1 affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< e4a5b01e59f7102169762b8f566c8e052d05c0ff affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 3340b8565b85631cfeb0df049e8b46e3ef8bd7bd affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 28a57fb2c5df4deb42a06e52fd36c14b37aa0034 affected
2.6.12 affected
< 2.6.12 unaffected
6.12.111≤ 6.12.* unaffected
6.18.53≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-98401

Vulnerability Information
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Vulnerability Title
net: iptunnel: fix stale transport header during tunnel decapsulation
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net: iptunnel: fix stale transport header during tunnel decapsulation Syzbot reported a crash in qdisc_pkt_len_segs_init() caused by a stale transport_header offset after tunnel decapsulation. BUG: unable to handle page fault for address: ffffed102091a42e Oops: Oops: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 340 Comm: qdisc_uaf_repro Not tainted 7.2.0-rc4-00061-g248951ddc14d #256 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:__asan_load2 <IRQ> qdisc_pkt_len_segs_init (net/core/dev.c:4145) __dev_queue_xmit (net/core/dev.c:4787) br_dev_queue_push_xmit (net/bridge/br_forward.c:53) br_handle_frame_finish (net/bridge/br_input.c:229) br_handle_frame (net/bridge/br_input.c:315) __netif_receive_skb_core.constprop.0 (net/core/dev.c:6099) __netif_receive_skb_list_core (net/core/dev.c:6287) netif_receive_skb_list_internal (net/core/dev.c:6445) napi_complete_done (net/core/dev.c:6813) gro_cell_poll (net/core/gro_cells.c:74) __napi_poll (net/core/dev.c:7735) net_rx_action (net/core/dev.c:7798 net/core/dev.c:7955) handle_softirqs (kernel/softirq.c:622) do_softirq (kernel/softirq.c:523 kernel/softirq.c:510 ) __local_bh_enable_ip (kernel/softirq.c:450) tun_get_user (drivers/net/tun.c:1986 (discriminator 1)) tun_chr_write_iter (drivers/net/tun.c:2032) The issue is completely latent until qdisc read transport header in commit 7fb4c1967011 ("net: pull headers in qdisc_pkt_len_segs_init()"). The crash requires four conditions to line up: 1. The incoming packet is encapsulated and carries GSO metadata. The outer transport header offset is stored in skb->transport_header while the packet is still in the outer tunnel context. 2. The tunnel receiver strips the outer headers. skb->data is advanced to the inner frame, but skb->transport_header is left pointing to the now-removed outer L4 header, so it becomes a negative offset relative to the new data. 3. The inner frame is not delivered to the local IP stack. Instead, it is forwarded at L2 by a bridge or HSR, so ip_rcv_core() never runs and the transport header is not reset to the inner L4 offset. 4. The forwarding path calls __dev_queue_xmit(), which enters qdisc_pkt_len_segs_init(). That function computes the GSO header length from skb_transport_offset(skb). Because the offset is negative, the unsigned cast overflows and pskb_may_pull(skb, hdr_len + sizeof(struct tcphdr)) reads past the end of the skb, triggering a KASAN fault or page fault. The issue specifically requires GSO packets (shinfo->gso_size != 0), which are processed/aggregated through gro_cells. Fix this by clearing transport_header to the ~0U sentinel in gro_cell for all tunnnel driver. GTP does not support GRO/GSO, drop the evil GSO packets in GTP directly.
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

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ~ 8c3d4dfcecf7670c1d752f1ae74b21b2af5feac1 -
Linux Linux 2.6.12 -

II. Public POCs for CVE-2026-98401

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III. Intelligence Information for CVE-2026-98401

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Other References for CVE-2026-98401 (4)

Same Patch Batch · Linux · 2026-10-14 · 46 CVEs total

CVE-2026-98398 locking/lockdep: Invalidate stale class_cache entries for zapped classes
CVE-2026-98396 powerpc: Do not restore KUAP in arch_exit_to_user_mode_prepare()
CVE-2026-98393 net: ipv4: Fix UDP length overflow with PMTU discover and big MTU
CVE-2026-98391 drm/xe: Guard page-fault worker with runtime PM check
CVE-2026-98389 drm/amdgpu: skip gfx switch_power_profile during GPU reset
CVE-2026-98388 exec: do_close_on_exec() before taking exec_update_lock
CVE-2026-98387 s390/crypto: Fix skcipher_walk return code handling in aes_s390
CVE-2026-98386 scsi: qla2xxx: Use memset_io() to clear QLAFX00 request ring slot
CVE-2026-98390 x86/amd_node: Avoid divide by zero on virtualized systems
CVE-2026-98397 platform/x86: x86-android-tablets: hold device reference for secondary fwnode teardown
CVE-2026-98395 powerpc/entry: Fix irq_soft_mask corruption on replayed interrupt exit
CVE-2026-98399 s390/ipl: Fix NULL deref in dump_reipl without re-IPL parm block
CVE-2026-98400 s390/ipl: Fix NULL deref in kdump without re-IPL parm block
CVE-2026-98402 net: icmp: avoid invalid transport header access in icmp_send tracepoint
CVE-2026-98403 s390/boot: Avoid IPL parameter append past command line
CVE-2026-98404 drm/virtio: Fix a NULL vs ERR_PTR() bug in virtio_gpu_user_framebuffer_create()
CVE-2026-98405 smb: client: fix missing iov bounds check in parse_posix_sids()
CVE-2026-98406 wifi: mac80211: avoid WARN in set_bitrate_mask when sdata not in driver
CVE-2026-98408 watchdog: rzv2h: Avoid division by zero
CVE-2026-98407 wifi: rsi: fix heap OOB write on key removal

Showing top 20 of 46 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98401

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