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CVE-2026-74544— net/sched: cls_u32: validate offshift to prevent shift-out-of-bounds

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u32_change()函数未对用户提供的offshift参数进行边界验证，可能导致越界移位。

CVSS 7.8 · High EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< 313cb9ffc4101a885d791facf4b5ea3d5e06144d affected
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2< aef96eead2860cbfa371e4471d4f04412213b958 affected
2.6.12 affected
< 2.6.12 unaffected
7.1.8≤ 7.1.* unaffected
7.2≤ * unaffected
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I. Basic Information for CVE-2026-74544

Vulnerability Information
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Vulnerability Title
net/sched: cls_u32: validate offshift to prevent shift-out-of-bounds
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_u32: validate offshift to prevent shift-out-of-bounds u32_change() copies the user-provided tc_u32_sel.offshift (unsigned char, 0-255) into the kernel knode object without bounds validation. When a packet later hits u32_classify() with TC_U32_VAROFFSET set, it evaluates `ntohs(offmask & *data) >> offshift` where the left operand is a 16-bit value promoted to a 32-bit int. Any offshift >= 32 is undefined behavior per C11 6.5.7p3, triggerable by an unprivileged user via user/network namespaces. UBSAN: shift-out-of-bounds in net/sched/cls_u32.c:236:43 shift exponent 32 is too large for 32-bit type int Fix this by rejecting offshift >= 16 during filter creation in u32_change().
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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u32_change()函数未对用户提供的offshift参数进行边界验证，可能导致越界移位。
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 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 ~ 313cb9ffc4101a885d791facf4b5ea3d5e06144d -
Linux Linux 2.6.12 -

II. Public POCs for CVE-2026-74544

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III. Intelligence Information for CVE-2026-74544

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Patches & Fixes for CVE-2026-74544 (2)

Same Patch Batch · Linux · 2026-08-15 · 845 CVEs total

CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-72084 9.8 CRITICAL scsi: target: Bound PR-OUT TransportID parsing to the received buffer
CVE-2026-72249 9.8 CRITICAL netfilter: flowtable: use dst in this direction when pushing IPIP header
CVE-2026-72248 9.8 CRITICAL netfilter: flowtable: support IPIP tunnel with direct xmit
CVE-2026-72098 9.8 CRITICAL dm-verity: fix buffer overflow in FEC calculation
CVE-2026-72494 9.8 CRITICAL RDMA/irdma: Replace waitqueue and flag with completion
CVE-2026-74345 9.8 CRITICAL RDMA/siw: Fix endpoint/socket association handling
CVE-2026-74255 9.8 CRITICAL tipc: fix UAF in tipc_l2_send_msg()
CVE-2026-72221 9.8 CRITICAL sunrpc: wait for in-flight TLS handshake callback when cancel loses race
CVE-2026-74428 9.8 CRITICAL rxrpc: Fix double unlock in rxrpc_recvmsg()
CVE-2026-72226 9.8 CRITICAL batman-adv: tt: prevent TVLV OOB check overflow
CVE-2026-72083 9.8 CRITICAL scsi: target: core: Fix iSCSI ISID use-after-free in REGISTER AND MOVE
CVE-2026-72234 9.8 CRITICAL batman-adv: access unicast_ttvn skb->data only after skb realloc

Showing top 20 of 845 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-74544

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