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CVE-2026-80905— net: tap: fix wrong transport_header when sending VLAN-tagged frame

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基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于在tap_get_user_xdp()处理VLAN标签帧时，skb_probe_transport_header()调用顺序不当，导致transport_header未被正确设置，可能引起网络数据包解析异常。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.15% · P5

Possible ATT&CK Techniques 1 AI

T1210.003

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 8c76e77f9069f10505c08e02646c3ee11ad79038< 5ffaa5d7f56ab24a8e23cf131eadfef31a3bbc4b affected
8c76e77f9069f10505c08e02646c3ee11ad79038< 88b79ac89ecc04d7f2613f7e1c0b46f0c4ddb2f3 affected
8c76e77f9069f10505c08e02646c3ee11ad79038< cbb35cbe8db268fefe34c23df15348cf99025298 affected
3cae5ef1f37a475faf7c40bc6a3c170779f3e0b1 affected
4.20.1< 4.21 affected
5.0 affected
< 5.0 unaffected
6.18.46≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-80905

Vulnerability Information
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Vulnerability Title
net: tap: fix wrong transport_header when sending VLAN-tagged frame
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net: tap: fix wrong transport_header when sending VLAN-tagged frame In tap_get_user_xdp(), when processing a VLAN-tagged frame (e.g. ETH_P_8021Q), skb_set_network_header() is called first to advance network_header past the VLAN tag to the inner protocol header. skb_probe_transport_header() is then called with skb->protocol still set to ETH_P_8021Q, while nhoff (derived from skb_network_offset()) already points past the VLAN tag to the inner protocol header. In __skb_flow_dissect(), proto is initialized to ETH_P_8021Q and nhoff points past the VLAN tag. When the dissector hits case ETH_P_8021Q, it reads a struct vlan_hdr at the current nhoff via __skb_header_pointer(), but that offset contains the inner protocol header (e.g. an IP header). The bytes are misinterpreted as a VLAN header, yielding a garbage encapsulated EtherType that matches no known protocol. The dissector returns false, so skb_probe_transport_header() never calls skb_set_transport_header(), leaving transport_header at its uninitialized sentinel value (~0U). Move skb_set_network_header() to after skb_probe_transport_header(). At the time skb_probe_transport_header() is called, network_header still points to the VLAN header (offset ETH_HLEN), so nhoff is correct and the flow dissector can parse the VLAN header, extract the inner EtherType, and advance nhoff to the inner protocol header, allowing transport_header to be set correctly.
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基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于在tap_get_user_xdp()处理VLAN标签帧时，skb_probe_transport_header()调用顺序不当，导致transport_header未被正确设置，可能引起网络数据包解析异常。
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 8c76e77f9069f10505c08e02646c3ee11ad79038 ~ 5ffaa5d7f56ab24a8e23cf131eadfef31a3bbc4b -
Linux Linux 5.0 -

II. Public POCs for CVE-2026-80905

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III. Intelligence Information for CVE-2026-80905

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Patches & Fixes for CVE-2026-80905 (3)

Same Patch Batch · Linux · 2026-09-04 · 156 CVEs total

CVE-2026-80864 RDMA/rxe: Fix responder UAF on IB_QP_MAX_DEST_RD_ATOMIC modify_qp
CVE-2026-80855 fuse: fix invalidate lock leak on open O_TRUNC DAX failure
CVE-2026-80856 fuse: fix invalidate lock leak on setattr writeback failure
CVE-2026-80857 fuse: wait for FR_FINISHED on abort_on_kill to prevent use-after-free
CVE-2026-80858 fuse: publish io-uring queues with release semantics
CVE-2026-80859 fuse: fix missing barrier when checking io-uring readiness
CVE-2026-80860 fuse: fix race between interrupt and resend
CVE-2026-80861 usb: xhci: bail out of setup if the controller is inaccessible
CVE-2026-80862 nvme-tcp: fix usage of page_frag_cache
CVE-2026-80863 RDMA/rxe: Fix OOB in free_rd_atomic_resources()
CVE-2026-80869 ntfs: bound the attribute-list entry in ntfs_read_inode_mount()
CVE-2026-80873 KVM: arm64: nv: Write ESR_EL2 for injected nested SError exceptions
CVE-2026-80872 ALSA: hda/tas2781: Cancel async firmware request at unbind
CVE-2026-80871 crypto: xilinx-trng - Remove crypto_rng interface
CVE-2026-80870 drm/amdkfd: Validate CRIU-restored IDs before idr_alloc
CVE-2026-80867 alpha/PCI: Add security_locked_down() check to pci_mmap_resource()
CVE-2026-80865 bpf: Add missing access_ok call to copy_user_syms
CVE-2026-80866 tipc: avoid busy looping in tipc_exit_net()
CVE-2026-80854 usb: gadget: f_tcm: keep port count until LUN teardown completes
CVE-2026-80868 ntfs3: Allocate iomap inline_data using alloc_page

Showing top 20 of 156 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-80905

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