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CVE-2025-37964— x86/mm: Eliminate window where TLB flushes may be inadvertently skipped

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.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于TLB刷新窗口过窄，可能导致跳过必要的刷新。

CVSS 7.8 · High EPSS 0.21% · P10

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 20

VendorProduct Version RangeStatus
Linux Linux 848b5815177582de0e1d0118725378e0fbadca20< 12f703811af043d32b1c8a30001b2fa04d5cd0ac affected
b47002ed65ade940839b7f439ff4a194e7d5ec28< 02ad4ce144bd27f71f583f667fdf3b3ba0753477 affected
a04fe3bfc71e28009e20357b79df1e8ef7c9d600< d41072906abec8bb8e01ed16afefbaa558908c89 affected
3dbe889a1b829b4c07e0836ff853fe649e51ce4f< d87392094f96e162fa5fa5a8640d70cc0952806f affected
6db2526c1d694c91c6e05e2f186c085e9460f202< 399ec9ca8fc4999e676ff89a90184ec40031cf59 affected
6db2526c1d694c91c6e05e2f186c085e9460f202< fea4e317f9e7e1f449ce90dedc27a2d2a95bee5a affected
d1347977661342cb09a304a17701eb2d4aa21dec affected
5.15.179< 5.15.183 affected
… +12 more rows
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I. Basic Information for CVE-2025-37964

Vulnerability Information
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Vulnerability Title
x86/mm: Eliminate window where TLB flushes may be inadvertently skipped
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: x86/mm: Eliminate window where TLB flushes may be inadvertently skipped tl;dr: There is a window in the mm switching code where the new CR3 is set and the CPU should be getting TLB flushes for the new mm. But should_flush_tlb() has a bug and suppresses the flush. Fix it by widening the window where should_flush_tlb() sends an IPI. Long Version: === History === There were a few things leading up to this. First, updating mm_cpumask() was observed to be too expensive, so it was made lazier. But being lazy caused too many unnecessary IPIs to CPUs due to the now-lazy mm_cpumask(). So code was added to cull mm_cpumask() periodically[2]. But that culling was a bit too aggressive and skipped sending TLB flushes to CPUs that need them. So here we are again. === Problem === The too-aggressive code in should_flush_tlb() strikes in this window: // Turn on IPIs for this CPU/mm combination, but only // if should_flush_tlb() agrees: cpumask_set_cpu(cpu, mm_cpumask(next)); next_tlb_gen = atomic64_read(&next->context.tlb_gen); choose_new_asid(next, next_tlb_gen, &new_asid, &need_flush); load_new_mm_cr3(need_flush); // ^ After 'need_flush' is set to false, IPIs *MUST* // be sent to this CPU and not be ignored. this_cpu_write(cpu_tlbstate.loaded_mm, next); // ^ Not until this point does should_flush_tlb() // become true! should_flush_tlb() will suppress TLB flushes between load_new_mm_cr3() and writing to 'loaded_mm', which is a window where they should not be suppressed. Whoops. === Solution === Thankfully, the fuzzy "just about to write CR3" window is already marked with loaded_mm==LOADED_MM_SWITCHING. Simply checking for that state in should_flush_tlb() is sufficient to ensure that the CPU is targeted with an IPI. This will cause more TLB flush IPIs. But the window is relatively small and I do not expect this to cause any kind of measurable performance impact. Update the comment where LOADED_MM_SWITCHING is written since it grew yet another user. Peter Z also raised a concern that should_flush_tlb() might not observe 'loaded_mm' and 'is_lazy' in the same order that switch_mm_irqs_off() writes them. Add a barrier to ensure that they are observed in the order they are written.
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
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于TLB刷新窗口过窄，可能导致跳过必要的刷新。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 848b5815177582de0e1d0118725378e0fbadca20 ~ 12f703811af043d32b1c8a30001b2fa04d5cd0ac -
Linux Linux 6.14 -

II. Public POCs for CVE-2025-37964

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III. Intelligence Information for CVE-2025-37964

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Same Patch Batch · Linux · 2025-05-20 · 95 CVEs total

CVE-2025-37894 9.8 CRITICAL net: use sock_gen_put() when sk_state is TCP_TIME_WAIT
CVE-2025-37924 9.8 CRITICAL ksmbd: fix use-after-free in kerberos authentication
CVE-2025-37935 9.8 CRITICAL net: ethernet: mtk_eth_soc: fix SER panic with 4GB+ RAM
CVE-2025-37959 9.4 CRITICAL bpf: Scrub packet on bpf_redirect_peer
CVE-2025-37926 8.8 HIGH ksmbd: fix use-after-free in ksmbd_session_rpc_open
CVE-2025-37899 8.8 HIGH ksmbd: fix use-after-free in session logoff
CVE-2025-37918 8.8 HIGH Bluetooth: btusb: avoid NULL pointer dereference in skb_dequeue()
CVE-2025-37943 8.8 HIGH wifi: ath12k: Fix invalid data access in ath12k_dp_rx_h_undecap_nwifi
CVE-2025-37944 8.8 HIGH wifi: ath12k: Fix invalid entry fetch in ath12k_dp_mon_srng_process
CVE-2025-37947 8.8 HIGH ksmbd: prevent out-of-bounds stream writes by validating *pos
CVE-2025-37952 8.8 HIGH ksmbd: Fix UAF in __close_file_table_ids
CVE-2025-37956 8.8 HIGH ksmbd: prevent rename with empty string
CVE-2025-37957 8.8 HIGH KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception
CVE-2025-37936 8.7 HIGH perf/x86/intel: KVM: Mask PEBS_ENABLE loaded for guest with vCPU's value.
CVE-2025-37973 8.1 HIGH wifi: cfg80211: fix out-of-bounds access during multi-link element defragmentation
CVE-2025-37903 7.8 HIGH drm/amd/display: Fix slab-use-after-free in hdcp
CVE-2025-37906 7.8 HIGH ublk: fix race between io_uring_cmd_complete_in_task and ublk_cancel_cmd
CVE-2025-37921 7.8 HIGH vxlan: vnifilter: Fix unlocked deletion of default FDB entry
CVE-2025-37923 7.8 HIGH tracing: Fix oob write in trace_seq_to_buffer()
CVE-2025-37920 7.8 HIGH xsk: Fix race condition in AF_XDP generic RX path

Showing top 20 of 95 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-37964

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