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CVE-2025-21971— net_sched: Prevent creation of classes with TC_H_ROOT

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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于net_sched模块允许创建TC_H_ROOT类，可能导致统计信息错误维护。

CVSS 7.8 · High EPSS 0.22% · P12

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 066a3b5b2346febf9a655b444567b7138e3bb939< e05d9938b1b0ac40b6054cc5fa0ccbd9afd5ed4c affected
066a3b5b2346febf9a655b444567b7138e3bb939< 7a82fe67a9f4d7123d8e5ba8f0f0806c28695006 affected
066a3b5b2346febf9a655b444567b7138e3bb939< 003d92c91cdb5a64b25a9a74cb8543aac9a8bb48 affected
066a3b5b2346febf9a655b444567b7138e3bb939< e5ee00607bbfc97ef1526ea95b6b2458ac9e7cb7 affected
066a3b5b2346febf9a655b444567b7138e3bb939< 78533c4a29ac3aeddce4b481770beaaa4f3bfb67 affected
066a3b5b2346febf9a655b444567b7138e3bb939< 5c3ca9cb48b51bd72bf76b8b05e24f3cd53db5e7 affected
066a3b5b2346febf9a655b444567b7138e3bb939< 94edfdfb9505ab608e86599d1d1e38c83816fc1c affected
066a3b5b2346febf9a655b444567b7138e3bb939< 0c3057a5a04d07120b3d0ec9c79568fceb9c921e affected
… +10 more rows
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I. Basic Information for CVE-2025-21971

Vulnerability Information
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Vulnerability Title
net_sched: Prevent creation of classes with TC_H_ROOT
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: net_sched: Prevent creation of classes with TC_H_ROOT The function qdisc_tree_reduce_backlog() uses TC_H_ROOT as a termination condition when traversing up the qdisc tree to update parent backlog counters. However, if a class is created with classid TC_H_ROOT, the traversal terminates prematurely at this class instead of reaching the actual root qdisc, causing parent statistics to be incorrectly maintained. In case of DRR, this could lead to a crash as reported by Mingi Cho. Prevent the creation of any Qdisc class with classid TC_H_ROOT (0xFFFFFFFF) across all qdisc types, as suggested by Jamal.
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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于net_sched模块允许创建TC_H_ROOT类，可能导致统计信息错误维护。
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 066a3b5b2346febf9a655b444567b7138e3bb939 ~ e05d9938b1b0ac40b6054cc5fa0ccbd9afd5ed4c -
Linux Linux 2.6.25 -

II. Public POCs for CVE-2025-21971

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III. Intelligence Information for CVE-2025-21971

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Patches & Fixes for CVE-2025-21971 (1)

Same Patch Batch · Linux · 2025-04-01 · 93 CVEs total

CVE-2025-21954 9.8 CRITICAL netmem: prevent TX of unreadable skbs
CVE-2025-21927 9.8 CRITICAL nvme-tcp: fix potential memory corruption in nvme_tcp_recv_pdu()
CVE-2025-21955 8.8 HIGH ksmbd: prevent connection release during oplock break notification
CVE-2025-21946 8.8 HIGH ksmbd: fix out-of-bounds in parse_sec_desc()
CVE-2025-21945 8.8 HIGH ksmbd: fix use-after-free in smb2_lock
CVE-2025-21969 8.8 HIGH Bluetooth: L2CAP: Fix slab-use-after-free Read in l2cap_send_cmd
CVE-2025-21967 8.8 HIGH ksmbd: fix use-after-free in ksmbd_free_work_struct
CVE-2025-21972 8.8 HIGH net: mctp: unshare packets when reassembling
CVE-2025-21947 8.1 HIGH ksmbd: fix type confusion via race condition when using ipc_msg_send_request
CVE-2025-21926 7.8 HIGH net: gso: fix ownership in __udp_gso_segment
CVE-2025-21970 7.8 HIGH net/mlx5: Bridge, fix the crash caused by LAG state check
CVE-2025-21899 7.8 HIGH tracing: Fix bad hist from corrupting named_triggers list
CVE-2025-21979 7.8 HIGH wifi: cfg80211: cancel wiphy_work before freeing wiphy
CVE-2025-21901 7.8 HIGH RDMA/bnxt_re: Add sanity checks on rdev validity
CVE-2025-21966 7.8 HIGH dm-flakey: Fix memory corruption in optional corrupt_bio_byte feature
CVE-2025-21965 7.8 HIGH sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl()
CVE-2025-21934 7.8 HIGH rapidio: fix an API misues when rio_add_net() fails
CVE-2025-21939 7.8 HIGH drm/xe/hmm: Don't dereference struct page pointers without notifier lock
CVE-2025-21958 7.8 HIGH Revert "openvswitch: switch to per-action label counting in conntrack"
CVE-2025-21949 7.8 HIGH LoongArch: Set hugetlb mmap base address aligned with pmd size

Showing top 20 of 93 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-21971

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