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CVE-2026-98038— bpf: Keep refcount_acquire nullable for borrowed RCU kptrs

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，已修复以下漏洞： bpf：使 对于借用的 RCU kptr 允许返回空指针 对于借用（borrowed）的引用是可能失败的，因为对象可能已经达到零引用计数。因此，除非参数是拥有所有权的引用（owning reference），否则验证器（verifier）会将返回值标记为 。 对局部 kptr 的 RCU 保护加载会被标记为 ，但只有当被指向的对象包含图节点（graph node）时，才会被标记为 。因此，没有图节点的引用计数对象即使其加载寄存器没有获得引用状态，也会被误认为是拥有所有权的引

AI Predicted 4.7 Difficulty: Hard EPSS 0.19% · P8

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 1b12171533a9bb23cf6fba7262b479028b65e1e8< 85074498228a2500ea8b8039c49cc1ab8ad5328f affected
1b12171533a9bb23cf6fba7262b479028b65e1e8< dc36739e5cc9f60485418a910b42bc95339218d2 affected
6.8 affected
< 6.8 unaffected
7.2.7≤ 7.2.* unaffected
7.3-rc2≤ * unaffected
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I. Basic Information for CVE-2026-98038

Vulnerability Information
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Vulnerability Title
bpf: Keep refcount_acquire nullable for borrowed RCU kptrs
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Keep refcount_acquire nullable for borrowed RCU kptrs bpf_refcount_acquire() is fallible for a borrowed reference because the object may have reached a zero refcount. The verifier therefore keeps KF_RET_NULL on the return value unless the argument is an owning reference. An RCU-protected load of a local kptr is marked MEM_ALLOC, but it only receives NON_OWN_REF when the pointee contains a graph node. A refcounted object without a graph node consequently looks like an owning reference even though the loaded register has no acquired reference state. If the program drops the last real reference while remaining in the RCU critical section, refcount_inc_not_zero() returns NULL while the verifier treats the result as non-NULL. Only classify the argument as owning when it is backed by a verifier-tracked reference. This retains the non-NULL return for pointers from bpf_obj_new(), bpf_kptr_xchg(), or an earlier successful acquisition, while requiring a NULL check for borrowed RCU kptrs. [ kkd: Rewrote commit log ]
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

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 1b12171533a9bb23cf6fba7262b479028b65e1e8 ~ 85074498228a2500ea8b8039c49cc1ab8ad5328f -
Linux Linux 6.8 -

II. Public POCs for CVE-2026-98038

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III. Intelligence Information for CVE-2026-98038

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Patches & Fixes for CVE-2026-98038 (2)

Same Patch Batch · Linux · 2026-09-25 · 372 CVEs total

CVE-2026-100075 9.8 CRITICAL RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters
CVE-2026-97555 8.8 HIGH smb: client: fix heap overflow in DACL owner/group rewrite
CVE-2026-97957 8.8 HIGH net: hinic: fix mailbox segment buffer overflow
CVE-2026-97527 8.8 HIGH scsi: qla2xxx: Serialize NVMe unsol ctx list with a per-fcport lock
CVE-2026-97528 8.8 HIGH scsi: qla2xxx: Unlink NVMe unsol ctx before freeing on LS reject error
CVE-2026-98115 8.8 HIGH ksmbd: safely drain sessions during logoff
CVE-2026-97525 8.2 HIGH x86/mm/pat: Allocate split page tables as kernel page tables
CVE-2026-98069 8.1 HIGH net/rds: acquire the fastpath locks in rds_conn_shutdown()
CVE-2026-97573 8.1 HIGH bnxt_en: Handle buffer allocation failure in bnxt_rx_ring_reset()
CVE-2026-97570 8.1 HIGH bnxt_en: Bound SW TPA IDs to prevent crashes
CVE-2026-98130 8.1 HIGH sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START
CVE-2026-98070 8.1 HIGH net/rds: acquire RDS_IN_XMIT in rds_tcp_reset_callbacks()
CVE-2026-98002 7.8 HIGH iommu/amd: Fix ineffective error check in nested domain allocation
CVE-2026-97575 7.8 HIGH media: v4l2-ctrls: validate AV1 tile counts
CVE-2026-97576 7.8 HIGH media: v4l2-ctrls: validate HEVC tile counts
CVE-2026-97941 7.8 HIGH mm/slab: take n->list_lock in __slab_try_return_freelist() to avoid race
CVE-2026-98112 7.8 HIGH ksmbd: fix listener task lifetime on netdev events
CVE-2026-97937 7.8 HIGH ftrace: fork: Initialize function graph state before copy_exec_state()
CVE-2026-97580 7.8 HIGH media: rkvdec: bound HEVC tile loops and PPS id to the array capacity
CVE-2026-97940 7.8 HIGH ipv6: fix fib6 walker UAF on seq stop

Showing top 20 of 372 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98038

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