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CVE-2026-98442— net/sched: act_ct: fix helper UAF due to extensions realloc

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_ct：修复因扩展区重新分配导致的 helper 使用后释放（UAF）问题 在调用 helper 时，扩展区域的原始指针被直接写入期望（expectation）列表中： 如果连接尚未确认，后续可能会通过 调用添加更多扩展，这些调用会重新分配扩展空间，导致期望列表中残留一个现已无效的指针。该指针随后在删除期望时被访问，从而引发使用后释放（Use-After-Free, UAF）漏洞。 修复方案：确保在所有其他扩展添加完成之后，再调用 helpe

CVSS 7.8 · High EPSS 0.13% · P3

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux a21b06e7319129994f339ed47f512bbe57b77f5b< 31f5fe29a572037ee19c233dfe506849940c484b affected
a21b06e7319129994f339ed47f512bbe57b77f5b< 1679bbf5fbeac52a310b1a58b2b301bbf388bdbf affected
a21b06e7319129994f339ed47f512bbe57b77f5b< 812c16a255e7773a544e88b39ae6daed25544d30 affected
a21b06e7319129994f339ed47f512bbe57b77f5b< 8988f4d11f3fba0ab38122178836c683ad516a05 affected
a21b06e7319129994f339ed47f512bbe57b77f5b< dad19b59da050cb60d3f7023dac2a042a84bf0bd affected
6.2 affected
< 6.2 unaffected
6.6.160≤ 6.6.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-98442

Vulnerability Information
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Vulnerability Title
net/sched: act_ct: fix helper UAF due to extensions realloc
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: fix helper UAF due to extensions realloc While calling the helpers, a raw pointer to the extensions area is wired into expectations list: -> nf_ct_helper() -> helper->help() -> nf_ct_expect_related_report() -> nf_ct_expect_insert() -> hlist_add_head_rcu(&exp->lnode, &master_help->expectations) In case the connection is not confirmed yet, more extensions can be added afterwards with *_ext_add() calls reallocating the extension space and leaving the now invalid pointer in the expectations list that is later accessed while removing the expectation. Make sure that helpers are called at the end after all the other extensions are already added. Note that the helper rejection now leaves the mark and labels set, but that's not different from how the NAT was handled before or how the mark and the labels were handled on confirmation failure. And there are no atomicity guarantees provided by the API anyway.
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 a21b06e7319129994f339ed47f512bbe57b77f5b ~ 31f5fe29a572037ee19c233dfe506849940c484b -
Linux Linux 6.2 -

II. Public POCs for CVE-2026-98442

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III. Intelligence Information for CVE-2026-98442

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Patches & Fixes for CVE-2026-98442 (5)

Same Patch Batch · Linux · 2026-10-18 · 435 CVEs total

CVE-2026-98548 9.8 CRITICAL sctp: discard the rest of the packet on a stale-cookie error
CVE-2026-98490 9.8 CRITICAL net: openvswitch: conntrack: fix helper UAF due to extensions realloc
CVE-2026-98464 9.3 CRITICAL RISC-V: KVM: Synchronize hrtimer callback during teardown
CVE-2026-98549 9.1 CRITICAL tcp: prevent collapsing skbs across boundary in rtx queue
CVE-2026-98451 8.8 HIGH smb: client: use finish_no_open() for non-regular inodes
CVE-2026-98466 8.2 HIGH KVM: arm64: Transfer the hyp stack pages out of the host stage-2
CVE-2026-98532 8.1 HIGH ipv6: do not let ipv6_find_hdr() return an offset past the packet end
CVE-2026-98499 8.1 HIGH HID: wacom: fix OOB read in wacom_wac_pen_serial_enforce()
CVE-2026-98454 8.1 HIGH smb: client: fix create context out-of-bounds reads
CVE-2026-98524 7.8 HIGH rds: ib: Clear the sg list when mapping an MR fails
CVE-2026-98520 7.8 HIGH drm/amdkfd: fix use-after-free and multi-container gap in kfd_dev_mapping
CVE-2026-98491 7.8 HIGH net: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry
CVE-2026-98507 7.8 HIGH mm/rmap: fix missing barrier between anon_vma init and vma->anon_vma publish
CVE-2026-98436 7.8 HIGH accel/amdxdna: Disable device buffer exporting
CVE-2026-98510 7.8 HIGH drm/xe/vm: nuke PTs only after unlinking contested VMAs
CVE-2026-98515 7.8 HIGH drm/nouveau: fix double-free in nvif_vmm_dtor
CVE-2026-98487 7.8 HIGH net: bridge: mdb: restart port group walk after deletion
CVE-2026-98517 7.8 HIGH drm/nouveau/uvmm: fix UAF in nouveau_uvmm_sm when BO is in TTM_PL_SYSTEM
CVE-2026-98443 7.8 HIGH xfs: fix cursor and pointer handling when recovering iunlink buckets
CVE-2026-98441 7.8 HIGH net/sched: act_ct: avoid modifying shared unconfirmed ct entry

Showing top 20 of 435 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux