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CVE-2025-37953— sch_htb: make htb_deactivate() idempotent

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sch_htb中htb_deactivate非幂等。

AI Predicted 5.5 Difficulty: Easy EPSS 0.19% · P9

Possible ATT&CK Techniques 1 AI

T1564.004 · NTFS File Attributes

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux e6b45f4de763b00dc1c55e685e2dd1aaf525d3c1< 99ff8a20fd61315bf9ae627440a5ff07d22ee153 affected
32ae12ce6a9f6bace186ca7335220ff59b6cc3cd< a9945f7cf1709adc5d2d31cb6cfc85627ce299a8 affected
967955c9e57f8eebfccc298037d4aaf3d42bc1c9< c2d25fddd867ce20a266806634eeeb5c30cb520c affected
73cf6af13153d62f9b76eff422eea79dbc70f15e< c928dd4f6bf0c25c72b11824a1e9ac9bd37296a0 affected
bbbf5e0f87078b715e7a665d662a2c0e77f044ae< 31ff70ad39485698cf779f2078132d80b57f6c07 affected
0a188c0e197383683fd093ab1ea6ce9a5869a6ea< 98cd7ed92753090a714f0802d4434314526fe61d affected
a61f1b5921761fbaf166231418bc1db301e5bf59< c4792b9e38d2f61b07eac72f10909fa76130314b affected
5ba8b837b522d7051ef81bacf3d95383ff8edce5< 3769478610135e82b262640252d90f6efb05be71 affected
… +4 more rows
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I. Basic Information for CVE-2025-37953

Vulnerability Information
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Vulnerability Title
sch_htb: make htb_deactivate() idempotent
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: sch_htb: make htb_deactivate() idempotent Alan reported a NULL pointer dereference in htb_next_rb_node() after we made htb_qlen_notify() idempotent. It turns out in the following case it introduced some regression: htb_dequeue_tree(): |-> fq_codel_dequeue() |-> qdisc_tree_reduce_backlog() |-> htb_qlen_notify() |-> htb_deactivate() |-> htb_next_rb_node() |-> htb_deactivate() For htb_next_rb_node(), after calling the 1st htb_deactivate(), the clprio[prio]->ptr could be already set to NULL, which means htb_next_rb_node() is vulnerable here. For htb_deactivate(), although we checked qlen before calling it, in case of qlen==0 after qdisc_tree_reduce_backlog(), we may call it again which triggers the warning inside. To fix the issues here, we need to: 1) Make htb_deactivate() idempotent, that is, simply return if we already call it before. 2) Make htb_next_rb_node() safe against ptr==NULL. Many thanks to Alan for testing and for the reproducer.
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
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sch_htb中htb_deactivate非幂等。
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 e6b45f4de763b00dc1c55e685e2dd1aaf525d3c1 ~ 99ff8a20fd61315bf9ae627440a5ff07d22ee153 -
Linux Linux 6.1.138 ~ 6.1.139 -

II. Public POCs for CVE-2025-37953

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III. Intelligence Information for CVE-2025-37953

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Patches & Fixes for CVE-2025-37953 (1)

Same Patch Batch · Linux · 2025-05-20 · 95 CVEs total

CVE-2025-37894 9.8 CRITICAL net: use sock_gen_put() when sk_state is TCP_TIME_WAIT
CVE-2025-37924 9.8 CRITICAL ksmbd: fix use-after-free in kerberos authentication
CVE-2025-37935 9.8 CRITICAL net: ethernet: mtk_eth_soc: fix SER panic with 4GB+ RAM
CVE-2025-37959 9.4 CRITICAL bpf: Scrub packet on bpf_redirect_peer
CVE-2025-37926 8.8 HIGH ksmbd: fix use-after-free in ksmbd_session_rpc_open
CVE-2025-37899 8.8 HIGH ksmbd: fix use-after-free in session logoff
CVE-2025-37918 8.8 HIGH Bluetooth: btusb: avoid NULL pointer dereference in skb_dequeue()
CVE-2025-37943 8.8 HIGH wifi: ath12k: Fix invalid data access in ath12k_dp_rx_h_undecap_nwifi
CVE-2025-37944 8.8 HIGH wifi: ath12k: Fix invalid entry fetch in ath12k_dp_mon_srng_process
CVE-2025-37947 8.8 HIGH ksmbd: prevent out-of-bounds stream writes by validating *pos
CVE-2025-37952 8.8 HIGH ksmbd: Fix UAF in __close_file_table_ids
CVE-2025-37956 8.8 HIGH ksmbd: prevent rename with empty string
CVE-2025-37957 8.8 HIGH KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception
CVE-2025-37936 8.7 HIGH perf/x86/intel: KVM: Mask PEBS_ENABLE loaded for guest with vCPU's value.
CVE-2025-37973 8.1 HIGH wifi: cfg80211: fix out-of-bounds access during multi-link element defragmentation
CVE-2025-37901 7.8 HIGH irqchip/qcom-mpm: Prevent crash when trying to handle non-wake GPIOs
CVE-2025-37906 7.8 HIGH ublk: fix race between io_uring_cmd_complete_in_task and ublk_cancel_cmd
CVE-2025-37921 7.8 HIGH vxlan: vnifilter: Fix unlocked deletion of default FDB entry
CVE-2025-37923 7.8 HIGH tracing: Fix oob write in trace_seq_to_buffer()
CVE-2025-37903 7.8 HIGH drm/amd/display: Fix slab-use-after-free in hdcp

Showing top 20 of 95 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-37953

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