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.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2025-1050 advisory.

    In the Linux kernel, the following vulnerability has been resolved:

    mm/vmscan: fix a bug calling wakeup_kswapd() with a wrong zone index (CVE-2024-26783)

    In the Linux kernel, the following vulnerability has been resolved:

    ipv6: Fix potential uninit-value access in __ip6_make_skb() (CVE-2024-36903)

    In the Linux kernel, the following vulnerability has been resolved:

    ipv4: Fix uninit-value access in __ip_make_skb() (CVE-2024-36927)

    In the Linux kernel, the following vulnerability has been resolved:

    bpf, arm64: Fix trampoline for BPF_TRAMP_F_CALL_ORIG (CVE-2024-43840)

    In the Linux kernel, the following vulnerability has been resolved:

    btrfs: don't BUG_ON() when 0 reference count at btrfs_lookup_extent_info() (CVE-2024-46751)

    In the Linux kernel, the following vulnerability has been resolved:

    sctp: add mutual exclusion in proc_sctp_do_udp_port() (CVE-2025-22062)

    In the Linux kernel, the following vulnerability has been resolved:

    ext4: fix off-by-one error in do_split (CVE-2025-23150)

    In the Linux kernel, the following vulnerability has been resolved:

    tracing: Fix oob write in trace_seq_to_buffer() (CVE-2025-37923)

    In the Linux kernel, the following vulnerability has been resolved:

    ftrace: Add cond_resched() to ftrace_graph_set_hash() (CVE-2025-37940)

    In the Linux kernel, the following vulnerability has been resolved:

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

    In the Linux kernel, the following vulnerability has been resolved:

    netfilter: ipset: fix region locking in hash types (CVE-2025-37997)

    In the Linux kernel, the following vulnerability has been resolved:

    net/tls: fix kernel panic when alloc_page failed (CVE-2025-38018)

    In the Linux kernel, the following vulnerability has been resolved:

    net/mlx5e: Disable MACsec offload for uplink representor profile (CVE-2025-38020)

    In the Linux kernel, the following vulnerability has been resolved:

    nfs: handle failure of nfs_get_lock_context in unlock path (CVE-2025-38023)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of kernel installed on the remote host is prior to 5.15.184-125.189. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2KERNEL-5.15-2025-078 advisory.

    In the Linux kernel, the following vulnerability has been resolved:

    btrfs: don't BUG_ON() when 0 reference count at btrfs_lookup_extent_info() (CVE-2024-46751)

    In the Linux kernel, the following vulnerability has been resolved:

    sctp: add mutual exclusion in proc_sctp_do_udp_port() (CVE-2025-22062)

    In the Linux kernel, the following vulnerability has been resolved:

    module: ensure that kobject_put() is safe for module type kobjects (CVE-2025-37995)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

An update of the linux package has been released.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2025-994 advisory.

    In the Linux kernel, the following vulnerability has been resolved:

    btrfs: do proper folio cleanup when cow_file_range() failed (CVE-2024-57976)

    In the Linux kernel, the following vulnerability has been resolved:

    kernel: be more careful about dup_mmap() failures and uprobe registering (CVE-2025-21709)

    In the Linux kernel, the following vulnerability has been resolved:

    block: fix queue freeze vs limits lock order in sysfs store methods (CVE-2025-21807)

    In the Linux kernel, the following vulnerability has been resolved:

    block: mark GFP_NOIO around sysfs ->store() (CVE-2025-21817)

    In the Linux kernel, the following vulnerability has been resolved:

    iommu/vt-d: Avoid use of NULL after WARN_ON_ONCE (CVE-2025-21833)

    In the Linux kernel, the following vulnerability has been resolved:

    net: better track kernel sockets lifetime (CVE-2025-21884)

    In the Linux kernel, the following vulnerability has been resolved:

    bnxt_en: Mask the bd_cnt field in the TX BD properly (CVE-2025-22108)

    In the Linux kernel, the following vulnerability has been resolved:

    ext4: goto right label 'out_mmap_sem' in ext4_setattr() (CVE-2025-22120)

    In the Linux kernel, the following vulnerability has been resolved:

    net_sched: hfsc: Fix a UAF vulnerability in class handling (CVE-2025-37797)

    In the Linux kernel, the following vulnerability has been resolved:

    vmxnet3: Fix malformed packet sizing in vmxnet3_process_xdp (CVE-2025-37799)

    In the Linux kernel, the following vulnerability has been resolved:

    usb: xhci: Fix invalid pointer dereference in Etron workaround (CVE-2025-37813)

    In the Linux kernel, the following vulnerability has been resolved:

    tty: Require CAP_SYS_ADMIN for all usages of TIOCL_SELMOUSEREPORT (CVE-2025-37814)

    In the Linux kernel, the following vulnerability has been resolved:

    perf/core: Fix WARN_ON(!ctx) in __free_event() for partial init (CVE-2025-37878)

    In the Linux kernel, the following vulnerability has been resolved:

    iommu: Fix two issues in iommu_copy_struct_from_user() (CVE-2025-37900)

    In the Linux kernel, the following vulnerability has been resolved:

    net_sched: qfq: Fix double list add in class with netem as child qdisc (CVE-2025-37913)

    In the Linux kernel, the following vulnerability has been resolved:

    net_sched: ets: Fix double list add in class with netem as child qdisc (CVE-2025-37914)

    In the Linux kernel, the following vulnerability has been resolved:

    net_sched: drr: Fix double list add in class with netem as child qdisc (CVE-2025-37915)

    In the Linux kernel, the following vulnerability has been resolved:

    xsk: Fix race condition in AF_XDP generic RX path (CVE-2025-37920)

    In the Linux kernel, the following vulnerability has been resolved:

    tracing: Fix oob write in trace_seq_to_buffer() (CVE-2025-37923)

    In the Linux kernel, the following vulnerability has been resolved:

    arm64: errata: Add missing sentinels to Spectre-BHB MIDR arrays (CVE-2025-37929)

    In the Linux kernel, the following vulnerability has been resolved:

    KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception (CVE-2025-37957)

    In the Linux kernel, the following vulnerability has been resolved:

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

    In the Linux kernel, the following vulnerability has been resolved:

    netfilter: ipset: fix region locking in hash types (CVE-2025-37997)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-5925 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-5925-1                   security@debian.org     https://www.debian.org/security/                     Salvatore Bonaccorso     May 24, 2025                          https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : linux     CVE ID         : CVE-2024-26618 CVE-2024-26783 CVE-2024-26807 CVE-2024-28956                      CVE-2024-35790 CVE-2024-36903 CVE-2024-36927 CVE-2024-43840                      CVE-2024-46751 CVE-2024-53203 CVE-2024-53209 CVE-2024-57945                      CVE-2025-21645 CVE-2025-21839 CVE-2025-21931 CVE-2025-22062                      CVE-2025-37819 CVE-2025-37890 CVE-2025-37897 CVE-2025-37901                      CVE-2025-37902 CVE-2025-37903 CVE-2025-37905 CVE-2025-37909                      CVE-2025-37911 CVE-2025-37912 CVE-2025-37913 CVE-2025-37914                      CVE-2025-37915 CVE-2025-37917 CVE-2025-37921 CVE-2025-37923                      CVE-2025-37924 CVE-2025-37927 CVE-2025-37928 CVE-2025-37929                      CVE-2025-37930 CVE-2025-37932 CVE-2025-37936 CVE-2025-37947                      CVE-2025-37948 CVE-2025-37949 CVE-2025-37951 CVE-2025-37953                      CVE-2025-37959 CVE-2025-37961 CVE-2025-37962 CVE-2025-37963                      CVE-2025-37964 CVE-2025-37967 CVE-2025-37969 CVE-2025-37970                      CVE-2025-37972 CVE-2025-37990 CVE-2025-37991

    Several vulnerabilities have been discovered in the Linux kernel that     may lead to a privilege escalation, denial of service or information     leaks.

    For CPUs affected to ITS (Indirect Target Selection), to fully mitigate     the vulnerability it is also necessary to update the intel-microcode     packages released in DSA 5924-1.

    For details on the Indirect Target Selection (ITS) vulnerability please     refer to https://www.vusec.net/projects/training-solo/ and     https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-     guidance/indirect-target-selection.html .

    For the stable distribution (bookworm), these problems have been fixed in     version 6.1.140-1.

    We recommend that you upgrade your linux packages.

    For the detailed security status of linux please refer to its security     tracker page at:
    https://security-tracker.debian.org/tracker/linux

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
241775	Amazon Linux 2023 : bpftool, kernel, kernel-devel (ALAS2023-2025-1050)	Nessus	Amazon Linux Local Security Checks	medium
241727	Amazon Linux 2 : kernel (ALASKERNEL-5.15-2025-078)	Nessus	Amazon Linux Local Security Checks	medium
240349	Photon OS 5.0: Linux PHSA-2025-5.0-0533	Nessus	PhotonOS Local Security Checks	high
238280	Amazon Linux 2023 : bpftool, kernel6.12, kernel6.12-modules-extra (ALAS2023-2025-994)	Nessus	Amazon Linux Local Security Checks	medium
237223	Debian dsa-5925 : affs-modules-6.1.0-33-4kc-malta-di - security update	Nessus	Debian Local Security Checks	medium

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