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CVE-2026-99018— riscv: entry: gate shadow call stack reload on sstatus.SPP, not tp

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： riscv: entry: 根据 sstatus.SPP 而非 tp 寄存器来重新加载门控影子调用栈 在启用 配置时， 函数仅当异常（trap）来自用户空间时，才会重新加载内核影子调用栈指针（即 gp 寄存器）。该函数原本通过 来判断是否来自用户空间：它将捕获时刻的 tp 值（从 sscratch 寄存器读回 s5）与当前的 tp 值进行比较： 然而，tp 是一个用户可写的寄存器。如果用户空间任务在触发异常前，将 tp 设置为自身 的线性映射地址（即 ），则上述比较将成

CVSS 7.8 · High EPSS 0.18% · P7

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux d1584d791a297aa8ed93503382a682a6ecfc4218< 6639735367a7d491977e9e5e7afc50b489d81d83 affected
d1584d791a297aa8ed93503382a682a6ecfc4218< 7d1367a53137e379498eb8791295e58854378636 affected
d1584d791a297aa8ed93503382a682a6ecfc4218< 37b4401ee6fa06046446d55e97e8d11784080843 affected
d1584d791a297aa8ed93503382a682a6ecfc4218< 4d0697f192975dab5985e921989be1d85cf580e9 affected
6.7 affected
< 6.7 unaffected
6.12.113≤ 6.12.* unaffected
6.18.57≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-99018

Vulnerability Information
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Vulnerability Title
riscv: entry: gate shadow call stack reload on sstatus.SPP, not tp
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: riscv: entry: gate shadow call stack reload on sstatus.SPP, not tp Under CONFIG_SHADOW_CALL_STACK, handle_exception() reloads the kernel shadow call stack pointer (gp) only when the trap came from userspace. It made that decision with scs_load_current_if_task_changed, which compares the trap-time tp (read back from sscratch into s5) against the current tp: beq \prev, tp, _skip_scs scs_load_current _skip_scs: tp is a user-writable register. A user task that sets tp to the linear-map address of its own task_struct (&current) before trapping makes the comparison succeed (can achieve by brute force with KASLR enable under our test), so the kernel skips scs_load_current and keeps running with the gp that userspace left in place. Under CONFIG_SHADOW_CALL_STACK gp is the shadow call stack pointer and load_global_pointer is a no-op, so the compiler-emitted "sd ra, -8(gp)" / "ld ra, -8(gp)" in every non-leaf function then write to, and return through, an attacker-controlled address -- an unprivileged kernel arbitrary-write and control-flow-hijack primitive. The poisoned gp is saved to task_struct.scs_sp on return, so the reload is skipped on every subsequent entry as well. Decide "came from userspace" from the hardware sstatus.SPP bit (already in s1 at this point) instead of from tp, mirroring the check that ret_from_exception already uses a few instructions later. SPP is written by hardware on trap entry and cannot be forged from U-mode. Legitimate behaviour is unchanged: user entries (SPP=0) reload the task shadow call stack, nested kernel entries (SPP=1) skip it.
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 d1584d791a297aa8ed93503382a682a6ecfc4218 ~ 6639735367a7d491977e9e5e7afc50b489d81d83 -
Linux Linux 6.7 -

II. Public POCs for CVE-2026-99018

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III. Intelligence Information for CVE-2026-99018

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Patches & Fixes for CVE-2026-99018 (4)

Same Patch Batch · Linux · 2026-10-23 · 217 CVEs total

CVE-2026-98959 9.8 CRITICAL btrfs: fix xattr replace when multiple xattrs are packed in the same item
CVE-2026-99078 9.8 CRITICAL net/mlx5e: Prevent stale XSK buffer release on MPWQE refill retry
CVE-2026-99079 9.8 CRITICAL net/mlx5e: Prevent stale XSK buffer release on refill retry
CVE-2026-98988 8.8 HIGH namespace: keep covered mounts covered in OPEN_TREE_NAMESPACE
CVE-2026-99083 8.8 HIGH ksmbd: fix heap out-of-bounds write in krb5_authenticate()
CVE-2026-99082 8.8 HIGH KVM: x86: Use active memslots for the per-vCPU MMIO cache
CVE-2026-98870 8.8 HIGH ksmbd: remove stale channels from all sessions on teardown
CVE-2026-98980 8.8 HIGH namei: don't reveal overmounted entries in refwalk
CVE-2026-98981 8.8 HIGH namespace: unhash a dentry before detaching the mounts on it
CVE-2026-99042 8.4 HIGH io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6
CVE-2026-98978 8.4 HIGH namespace: never expire a locked mount
CVE-2026-99064 8.1 HIGH cipso: adjust cached option offsets when removing CIPSO
CVE-2026-98968 8.1 HIGH amt: send the relay's General Query directly from the receive path
CVE-2026-99016 7.8 HIGH riscv: futex: untag the user pointer before the atomic access
CVE-2026-99012 7.8 HIGH Bluetooth: ISO: Serialize concurrent connect calls
CVE-2026-99002 7.8 HIGH drm/vmwgfx: validate pitch coming from userspace
CVE-2026-98899 7.8 HIGH netfilter: ipset: mark the rcu locked areas properly
CVE-2026-99006 7.8 HIGH drm/i915/gem: Prevent overstepping exec array boundary
CVE-2026-98999 7.8 HIGH drm/xe: Fix stale pinned_link entry when fb-pin performs the final unpin
CVE-2026-99032 7.8 HIGH net/smc: protect clcsock lifetime in smc_getname

Showing top 20 of 217 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

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