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CVE-2026-74739— net/sched: cls_u32: skip hash tables in u32_bind_class()

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.

以下是该漏洞描述的中文翻译： 在 Linux 内核中，已修复以下漏洞： net/sched: cls_u32: 在 中跳过哈希表 通过遍历回调函数同时枚举 和 。 无条件地将传入的 强制转换为 并访问 。因此，当 实际上是 （该结构体没有 成员）时，在 中访问 会导致 slab 内存越界读取。 该问题可通过以下命令复现： 通过 检查来跳过哈希表，从而修复此问题。

CVSS 7.8 · High EPSS 0.14% · P4

Possible ATT&CK Techniques 2 AI

T1624 T1203.001

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1< ec5f3005586a785689fd568361b0c5925cb1548b affected
07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1< 19d114b93c94bdef70496f26685c2a6b242f41b3 affected
07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1< 594a064d603202b9ee21e07679d854e5c1750cc4 affected
07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1< 31f26a95eeee926946809ac456c61a3217936a62 affected
07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1< e71f8e9ed6f311410b14741f6012afe01869c0fa affected
07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1< 6d3724e616faf952c3adcf8414fc21a828ef3709 affected
4.14 affected
< 4.14 unaffected
… +6 more rows
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I. Basic Information for CVE-2026-74739

Vulnerability Information
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Vulnerability Title
net/sched: cls_u32: skip hash tables in u32_bind_class()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_u32: skip hash tables in u32_bind_class() u32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode through the walker callback. u32_bind_class() unconditionally casts the passed fh to tc_u_knode and accesses &n->res, so when fh is actually a tc_u_hnode, which has no tcf_result member, this results in a slab-out-of-bounds read of res->classid in tc_cls_bind_class(). The issue can be reproduced with the following commands: tc qdisc add dev lo root handle 1: hfsc tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1 tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbit Fix this by skipping hash tables via the TC_U32_KEY(handle) check.
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

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 ~ ec5f3005586a785689fd568361b0c5925cb1548b -
Linux Linux 4.14 -

II. Public POCs for CVE-2026-74739

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III. Intelligence Information for CVE-2026-74739

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Patches & Fixes for CVE-2026-74739 (6)

Same Patch Batch · Linux · 2026-08-26 · 92 CVEs total

CVE-2026-80557 9.8 CRITICAL libceph: fix OOB read in decode_watchers() via missing bounds check
CVE-2026-74752 9.8 CRITICAL sctp: validate cookie AUTH state before use
CVE-2026-80589 9.8 CRITICAL block: stop the timeout timer when releasing a never added disk
CVE-2026-74737 9.8 CRITICAL net: ethernet: ti: am65-cpsw-nuss: Fix port_id extraction from SRC TAG
CVE-2026-80587 9.8 CRITICAL mptcp: avoid combining some incoming suboptions
CVE-2026-80558 9.8 CRITICAL libceph: Avoid using invalid osd indices from primary_temp
CVE-2026-80528 9.8 CRITICAL ceph: avoid fs reclaim while using current->journal_info
CVE-2026-74743 9.8 CRITICAL macvlan: inherit needed_headroom and needed_tailroom from lowerdev
CVE-2026-74744 9.8 CRITICAL ipvlan: inherit needed_headroom and needed_tailroom from phy_dev
CVE-2026-80586 9.8 CRITICAL mptcp: options: reset DSS fields in case of unexpected size
CVE-2026-74746 9.8 CRITICAL netfilter: flowtable: publish GC-visible tuple last
CVE-2026-80561 9.8 CRITICAL libceph: fix multiple unsafe decodes in decode_locker()
CVE-2026-80519 9.8 CRITICAL ovpn: finish crypto callback cleanup before peer release
CVE-2026-74751 9.4 CRITICAL riscv: lib: Fix ZBB strnlen reading past count boundary
CVE-2026-80585 9.4 CRITICAL mptcp: fastopen: only mark MPTFO subflows with SYN data
CVE-2026-80554 9.3 CRITICAL s390/vfio_ccw: Limit the number of channel program segments
CVE-2026-80551 9.3 CRITICAL s390/vfio_ccw: Ensure first IDAW remains constant
CVE-2026-80576 8.8 HIGH drm/amdgpu: reject oversized IBs with per-ring packet limits
CVE-2026-80553 8.8 HIGH s390/vfio_ccw: Cancel existing workqueues
CVE-2026-80547 8.8 HIGH s390/vfio_ccw: Implement a crw lock

Showing top 20 of 92 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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