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CVE-2026-89902— LoongArch: Avoid preempt count underflow without probe

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： LoongArch：避免在无探测情况下发生抢占计数下溢 LoongArch 架构使用 指令作为断点，该断点被放置在 Kprobes 执行“out-of-line”指令之后。由于用户空间程序也可能发出相同的 指令，当当前没有活动的探测点时， 仍可能进入 。 在这种“无当前探测点”的情况下，该处理函数最终会返回 ，但它首先调用了 。而与之配对的 通常是在真实的 Kprobe 命中时由 调用的。由于在当前场景下该配对调用未曾执行，导致一个普通的用户空间断点（code 11）会

CVSS 7.8 · High EPSS 0.18% · P6

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux 6d4cc40fb5f58147defc6c0e9d86e6232fe31616< ff40e597d5d98c0c45a4d09df8177202fac9520e affected
6d4cc40fb5f58147defc6c0e9d86e6232fe31616< a1cb727fa27c2d9c7859729cd90db7bc0f46957f affected
6d4cc40fb5f58147defc6c0e9d86e6232fe31616< 76395109a051b53860faaec96522ef08ae9e8e27 affected
6d4cc40fb5f58147defc6c0e9d86e6232fe31616< c4357ebeee63cb8da1446fc936573a34e68b0f71 affected
6d4cc40fb5f58147defc6c0e9d86e6232fe31616< 72ce4b24676e8b3b75376c4c559dd81c1ac52d5a affected
6.3 affected
< 6.3 unaffected
6.6.157≤ 6.6.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-89902

Vulnerability Information
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Vulnerability Title
LoongArch: Avoid preempt count underflow without probe
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: LoongArch: Avoid preempt count underflow without probe LoongArch uses break 11 for the breakpoint placed after an instruction that Kprobes executes out of line. Since userspace can issue the same break instruction, do_bp() can reach kprobe_singlestep_handler() when there is no current probe. The handler actually returns false in this case, but it first calls preempt_enable_no_resched(). The corresponding preempt_disable() is done by kprobe_breakpoint_handler() on a real Kprobe hit, so it has not run here. As a result, an ordinary userspace breakpoint (code 11) underflows the current task's preempt count. This also makes in_interrupt() return true until the task schedules. One visible consequence is the socket cgroup attribution: cgroup_sk_alloc() treats the allocation as interrupt context and assigns the socket to the root cgroup. A socket opened from the SIGTRAP handler can then avoid a BPF_CGROUP_INET_SOCK_CREATE policy attached to the task's own cgroup. Return as soon as kprobe_running() reports no active probe. The same check has appeared in [PATCH v10 2/4] of the original LoongArch Kprobes series, but was dropped before the feature reached mainline.
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 6d4cc40fb5f58147defc6c0e9d86e6232fe31616 ~ ff40e597d5d98c0c45a4d09df8177202fac9520e -
Linux Linux 6.3 -

II. Public POCs for CVE-2026-89902

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III. Intelligence Information for CVE-2026-89902

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Other References for CVE-2026-89902 (5)

Same Patch Batch · Linux · 2026-09-16 · 276 CVEs total

CVE-2026-90048 9.8 CRITICAL fs/ntfs3: fix slab-out-of-bounds write in ni_create_attr_list()
CVE-2026-90012 9.8 CRITICAL spi: Fix DMA mapping ownership on partial map failure
CVE-2026-89970 9.8 CRITICAL nvmet-auth: Synchronize timeout work during SQ teardown
CVE-2026-89857 9.8 CRITICAL scsi: qla2xxx: Hold qpair lock when sending NVMe LS reject
CVE-2026-89969 9.8 CRITICAL nvmet-tcp: fix out-of-bounds write when receiving an over-long PDU
CVE-2026-89847 9.8 CRITICAL scsi: qla2xxx: Avoid double completion in async IOCB timeout
CVE-2026-89972 9.8 CRITICAL nvme: add missing SRCU grace period in error path
CVE-2026-89990 9.8 CRITICAL ceph: lock mutex in ceph_mds_check_access()
CVE-2026-90036 9.8 CRITICAL NFSD: Prevent client use-after-free during blocked-lock reaping
CVE-2026-90038 9.8 CRITICAL NFSD: Prevent client use-after-free during export state revocation
CVE-2026-90037 9.8 CRITICAL NFSD: Prevent client use-after-free during close_lru reaping
CVE-2026-89788 9.8 CRITICAL ksmbd: fix tree connection use-after-free in smb2_tree_connect()
CVE-2026-89783 9.8 CRITICAL xfrm6: fix out-of-bounds write in xfrm6_input_addr() when secpath is full
CVE-2026-90042 9.8 CRITICAL ceph: properly decrypt filenames in vmalloc() buffers
CVE-2026-89778 9.8 CRITICAL isofs: fix out-of-bounds page array access on empty zisofs block
CVE-2026-89915 9.3 CRITICAL KVM: arm64: Remove VM-wide VNCR mapping counter
CVE-2026-90049 9.3 CRITICAL net: skbuff: don't skb_tx_error() the source skb in skb_zerocopy()
CVE-2026-89775 9.3 CRITICAL KVM: arm64: Handle negative S1 walk levels in VNCR TLB size evaluation
CVE-2026-89916 9.3 CRITICAL KVM: arm64: Make VNCR invalidation participate in MMU invalidation retry
CVE-2026-89930 9.3 CRITICAL KVM: nVMX: Service local TLB flushes on failed nested VM-Enter

Showing top 20 of 276 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-89902

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