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CVE-2026-90078— net/sched: act_skbmod: fix length calculations and avoid invalid header warnings

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.

在 Linux 内核中，以下漏洞已得到修复： net/sched: act_skbmod：修复长度计算并避免无效的头部警告 syzbot 报告了一个由 触发的 警告： 中存在以下几个问题： 1. 调用 时假设 已被设置，但在 TC 入站（ingress）场景下，这一点并非总是成立。 2. 在 开头无条件调用 ，会在 L3 设备（例如 TUN 设备）上触发警告，因为这类设备未设置 MAC 头部，导致返回一个下溢的垃圾长度值。 3. 在 TC 入站路径中， 指向网络层头部。将 MAC 头部长度加到 IP 头部长度上，会

AI Predicted 4.4 Difficulty: Hard EPSS 0.21% · P10

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 56af5e749f20c3a540310c207dcc373f4f09156e< 985a37781ade19061400100c2ba0f43979dd4d63 affected
56af5e749f20c3a540310c207dcc373f4f09156e< d896843d8d925f0adbba319020595cfb1a7bcd57 affected
56af5e749f20c3a540310c207dcc373f4f09156e< 0675cff3c2924eb9b80d9dd250cf56a1140af157 affected
56af5e749f20c3a540310c207dcc373f4f09156e< e8a2027b7e686784a69b2dfcee841d779919f313 affected
56af5e749f20c3a540310c207dcc373f4f09156e< 1719865b20b22c88d2a55e922eff5ca31b0841f6 affected
56af5e749f20c3a540310c207dcc373f4f09156e< 62126464f3a6159c0a3dd89e196ba65bfeb0afc6 affected
56af5e749f20c3a540310c207dcc373f4f09156e< 81d0d1e64f30d9989c829c0953cd6e6c68d9c5fb affected
5.15 affected
… +8 more rows
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I. Basic Information for CVE-2026-90078

Vulnerability Information
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Vulnerability Title
net/sched: act_skbmod: fix length calculations and avoid invalid header warnings
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_skbmod: fix length calculations and avoid invalid header warnings syzbot reported a warning in skb_network_header_len() triggered by tcf_skbmod_act(): !skb_transport_header_was_set(skb) WARNING: CPU: 0 PID: 14949 at include/linux/skbuff.h:3243 skb_network_header_len include/linux/skbuff.h:3243 [inline] WARNING: CPU: 0 PID: 14949 at net/sched/act_skbmod.c:55 tcf_skbmod_act+0xfe8/0x1810 net/sched/act_skbmod.c:55 There are a few issues in tcf_skbmod_act(): 1. Calling skb_network_header_len() assumes skb->transport_header is set, which is not guaranteed when tcf_skbmod_act() runs at TC ingress. 2. Unconditionally calling skb_mac_header_len() at the beginning of tcf_skbmod_act() triggers a warning on L3 devices (e.g. TUN) where the MAC header is unset, evaluating to an underflowed garbage length. 3. On TC ingress, skb->data points to the network header. Adding the MAC header length to the IP header length causes skb_ensure_writable() to request more bytes than the actual IP packet length, dropping valid short packets (e.g. 28-byte UDP/IPv4 packets). Fix these by: - Using skb_network_offset(skb) + sizeof(struct iphdr/ipv6hdr) for SKBMOD_F_ECN so that the required length is correctly calculated on both ingress (offset == 0) and egress (offset == mac_len). - Setting max_edit_len to ETH_HLEN for Ethernet header modifications after validating ARPHRD_ETHER.
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 56af5e749f20c3a540310c207dcc373f4f09156e ~ 985a37781ade19061400100c2ba0f43979dd4d63 -
Linux Linux 5.15 -

II. Public POCs for CVE-2026-90078

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III. Intelligence Information for CVE-2026-90078

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Patches & Fixes for CVE-2026-90078 (7)

Same Patch Batch · Linux · 2026-09-17 · 600 CVEs total

CVE-2026-90173 9.8 CRITICAL smb: smbdirect: free completion queues with ib_free_cq()
CVE-2026-92489 9.8 CRITICAL xfrm: Fix skb double-free in xfrm_dev_direct_output()
CVE-2026-90104 9.8 CRITICAL NFSv4.1: zero referring call lists before decoding
CVE-2026-90235 9.8 CRITICAL sunrpc: xprtsock: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE
CVE-2026-90151 9.8 CRITICAL NFSv4: remove callback IDR entry on client allocation failure
CVE-2026-90110 9.4 CRITICAL inetpeer: randomize RB-tree node comparison using SipHash
CVE-2026-90414 9.1 CRITICAL IB/isert: reject PDUs declaring more data than was received
CVE-2026-90413 9.1 CRITICAL IB/isert: reject login PDUs declaring more data than was received
CVE-2026-90230 9.1 CRITICAL nvmet: fix heap out-of-bounds read in nvmet_auth_negotiate()
CVE-2026-90381 8.8 HIGH wifi: mt76: fix handling channel context with different bands in mt76_switch_vif_chanctx()
CVE-2026-90329 8.8 HIGH HID: synchronize input before cleaning up a failed probe
CVE-2026-90162 8.8 HIGH ksmbd: defer publishing granted locks to prevent UAF/double-free race
CVE-2026-90357 8.8 HIGH wifi: mt76: mt7915: unlink TWT flow if the MCU rejects the agreement
CVE-2026-90367 8.8 HIGH wifi: mt76: mt7996: hold dev->mt76.mutex while disabling tx worker in SER
CVE-2026-90371 8.8 HIGH wifi: mt76: fix RXDMAD_C buffer recycling race
CVE-2026-93042 8.8 HIGH dmaengine: dw-edma: Terminate all descriptors without callbacks
CVE-2026-90425 8.8 HIGH iommu/tegra241-cmdqv: Require exactly one Stream ID for a vSID
CVE-2026-90240 8.8 HIGH iommu/vt-d: Flush context cache with correct SID when tearing down aliases
CVE-2026-90379 8.8 HIGH wifi: mt76: mt7921: Add PCIe AER handler support to prevent system crash
CVE-2026-90256 8.8 HIGH Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind

Showing top 20 of 600 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-90078

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