CVE-2026-63806— Linux kernel 安全漏洞
一分钟漏洞结论
影响对象
Linux Linux
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 2.6.32版本及之前版本存在安全漏洞，该漏洞源于ioeventfd datamatch机制中的BUG_ON()可达性问题，可能导致在未对齐访问时触发内核崩溃。
影响版本矩阵 18
| 厂商 | 产品 | 版本范围 | 状态 |
|---|---|---|---|
| Linux | Linux | d34e6b175e61821026893ec5298cc8e7558df43a< 2426c15c1395b7d5ccf1e5025ca898af7f3decb6 |
affected |
d34e6b175e61821026893ec5298cc8e7558df43a< 4186c850789906b875a1d263377a4d37c078e317 |
affected | ||
d34e6b175e61821026893ec5298cc8e7558df43a< 36ff44fb3d89960391e013fb9d91e23dbc48be47 |
affected | ||
d34e6b175e61821026893ec5298cc8e7558df43a< 92fc631b69deb1c7d56aec2663003600799dcd75 |
affected | ||
d34e6b175e61821026893ec5298cc8e7558df43a< bf89e3738480d33cd515b4a18900e8443d40cd2e |
affected | ||
d34e6b175e61821026893ec5298cc8e7558df43a< 5da9b1a87ec7cc3489c27016313524769f12d9e0 |
affected | ||
d34e6b175e61821026893ec5298cc8e7558df43a< 5c87b47374682f69686068ad0a7779365a527b1c |
affected | ||
d34e6b175e61821026893ec5298cc8e7558df43a< f1edbed787ba67988ed34e0132ca128b052b6ce8 |
affected | ||
| … +10 条更多 | |||
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一、 漏洞 CVE-2026-63806 基础信息
漏洞信息
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Vulnerability Title
KVM: Replace guest-triggerable BUG_ON() in ioeventfd datamatch with get_unaligned()
来源: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved:
KVM: Replace guest-triggerable BUG_ON() in ioeventfd datamatch with get_unaligned()
Drop a BUG_ON() that has been reachable since it was first added, way back
in 2009, and instead use get_unaligned() to perform potentially-unaligned
accesses.
For a given store, KVM x86's emulator tracks the entire value in the
destination operand, x86_emulate_ctxt.dst. If the destination is memory,
and the target splits multiple pages and/or is emulated MMIO, then KVM
handles each fragment independently. E.g. on a page split starting at page
offset 0xffc, KVM writes 4 bytes to the first page, then the remaining
bytes to the second page, using ctxt->dst as the source for both (with
appropriate offsets).
If the destination splits a page *and* hits emulated MMIO on the second
page, then KVM will complete the write to the first page, then emulate the
MMIO access to the second page. If there is a datamatch-enabled ioeventfd
at offset 0 of the second page, then KVM will process the remainder of the
store as a potential ioeventfd signal.
Putting it all together, if the guest emits a store that splits a page
starting at page offset N, and the second page has a datamatch-enabled
ioeventfd at offset 0, then KVM will check for datamatch using
&dst.valptr[N] as the source. Due to dst (and thus dst.valptr) being
32-byte aligned, if N is not aligned to @len, the BUG_ON() fires.
E.g. with a 16-byte store at page offset 0xffc, to an ioeventfd of len 8,
all initial checks in ioeventfd_in_range() will succeed, and the BUG_ON()
fires due to @val being 4-byte aligned, but not 8-byte aligned.
------------[ cut here ]------------
kernel BUG at arch/x86/kvm/../../../virt/kvm/eventfd.c:783!
Oops: invalid opcode: 0000 [#1] SMP
CPU: 0 UID: 1000 PID: 615 Comm: repro Not tainted 7.1.0-rc2-ff238429d1ea #365 PREEMPT
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:ioeventfd_write+0x6c/0x70 [kvm]
Call Trace:
<TASK>
__kvm_io_bus_write+0x85/0xb0 [kvm]
kvm_io_bus_write+0x53/0x80 [kvm]
vcpu_mmio_write+0x66/0xf0 [kvm]
emulator_read_write_onepage+0x12a/0x540 [kvm]
emulator_read_write+0x109/0x2b0 [kvm]
x86_emulate_insn+0x4f8/0xfb0 [kvm]
x86_emulate_instruction+0x181/0x790 [kvm]
kvm_mmu_page_fault+0x313/0x630 [kvm]
vmx_handle_exit+0x18a/0x590 [kvm_intel]
kvm_arch_vcpu_ioctl_run+0xc81/0x1c90 [kvm]
kvm_vcpu_ioctl+0x2d5/0x970 [kvm]
__x64_sys_ioctl+0x8a/0xd0
do_syscall_64+0xb7/0x890
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7f19c931a9bf
</TASK>
Modules linked in: kvm_intel kvm irqbypass
---[ end trace 0000000000000000 ]---
In a perfect world, the fix would be to simply delete the BUG_ON(), as KVM
x86 doesn't perform alignment checks on "normal" memory accesses at CPL0.
Sadly, C99 ruins all the fun; while the x86 architecture plays nice,
dereferencing an unaligned pointer directly is undefined behavior in C,
e.g. triggers splats when running with CONFIG_UBSAN_ALIGNMENT=y.
来源: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
来源: CVE Program / CVE List V5
Vulnerability Type
N/A
来源: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 2.6.32版本及之前版本存在安全漏洞，该漏洞源于ioeventfd datamatch机制中的BUG_ON()可达性问题，可能导致在未对齐访问时触发内核崩溃。
来源: 中国国家信息安全漏洞库 CNNVD
CVSS Information
N/A
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Type
N/A
来源: 中国国家信息安全漏洞库 CNNVD
受影响产品
二、漏洞 CVE-2026-63806 的公开POC
| # | POC 描述 | 源链接 | 神龙链接 |
|---|
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CVE-2026-63806 补丁与修复 (8)
同批安全公告 · Linux · 2026-07-19 · 共 429 条
| CVE-2026-63795 | 10.0 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64033 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-53399 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-53398 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64037 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63984 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63979 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64056 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63800 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63978 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63808 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64055 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64142 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64089 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63922 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64091 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64160 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64035 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-63888 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
| CVE-2026-64162 | 9.8 CRITICAL | Linux kernel 安全漏洞 |
显示前 20 条，共 429 条。 查看全部 → →
IV. Related Vulnerabilities
V. Comments for CVE-2026-63806
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