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CVE-2026-98084— bpf: backtracking shouldn't clear outer frame R1-R5 for callbacks

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： bpf：回溯时不应清除回调函数外部帧的 R1-R5 寄存器状态 在处理 调用时，验证器（verifier）会将寄存器 R1（以及 R4）标记为“精确”（precise）。其中，R1 用于跟踪循环迭代次数；由于 中存在 的逻辑机制，R1 必须被标记为精确。然而，当 调用在第二次迭代期间进行验证时，R1 的精度传播机制出现了故障。 请考虑以下验证过程追踪示例： 主函数： 回调函数： 主函数： ... 当第一次访问 调用时，R1 的精度按预期进行了传播。然而，在 中第二次调用

AI Predicted 7.8 Difficulty: Moderate EPSS 0.15% · P4

Possible ATT&CK Techniques 1 AI

T1200 · Hardware Additions

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux ab5cfac139ab8576fb54630d4cca23c3e690ee90< f83890dfed9efc5e19df1dbc1ad707a142936923 affected
ab5cfac139ab8576fb54630d4cca23c3e690ee90< e3e4f66cc4b72333d0886ae2673c360248987889 affected
b43550d7d58e7ae6618aaab18c1e912fa4d6e3dd affected
6.6.15< 6.7 affected
6.7 affected
< 6.7 unaffected
7.2.7≤ 7.2.* unaffected
7.3-rc2≤ * unaffected
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I. Basic Information for CVE-2026-98084

Vulnerability Information
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Vulnerability Title
bpf: backtracking shouldn't clear outer frame R1-R5 for callbacks
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: bpf: backtracking shouldn't clear outer frame R1-R5 for callbacks When processing calls to bpf_loop() verifier marks R1 (and R4) as precise. R1 tracks loop iterations number and because of the 'callback_depth < R1' mechanics in check_helper_call() must be marked precise. However, precision propagation for R1 was broken, when bpf_loop() call was verified on a second iteration. Consider the following verification trace: - main: bpf_loop(nr_loops, callback ...) - callback: BPF_EXIT - main: bpf_loop(nr_loops, callback ...) - ... While the first visit of the call to bpf_loop() propagated R1 precision as expected, the second call to mark_chain_precision() in the check_helper_call() set R1, but it was immediately reset when backtrack_insn() processed preceding BPF_EXIT in the loop deleted in this patch. Because of that, the second visit of the call to bpf_loop() injected checkpoint with R1 not marked as precise. Which could trick the verifier into accepting unsafe programs. See the next patch for an example of such program. Commit is structured in a way to minimize conflicts when 'bpf' would be eventually merged with 'bpf-next'.
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 ab5cfac139ab8576fb54630d4cca23c3e690ee90 ~ f83890dfed9efc5e19df1dbc1ad707a142936923 -
Linux Linux 6.7 -

II. Public POCs for CVE-2026-98084

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III. Intelligence Information for CVE-2026-98084

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Patches & Fixes for CVE-2026-98084 (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

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