The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-63806)

Note that Nessus relies on the presence of the package as reported by the vendor.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1969 advisory.

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

    sctp: disable BH before calling udp_tunnel_xmit_skb() (CVE-2026-53070)

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

    bpf: Fix same-register dst/src OOB read and pointer leak in sock_ops (CVE-2026-53078)

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

    KVM: x86: Fix shadow paging use-after-free due to unexpected role (CVE-2026-53359)

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

    af_unix: Set gc_in_progress to true in unix_gc(). (CVE-2026-53361)

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

    virtiofs: fix UAF on submount umount

    iput() called from fuse_release_end() can Oops if the super block hasalready been destroyed.  Normally     this is prevented by waiting fornum_waiting to go down to zero before commencing with super block     shutdown.

    This only works, however, for the last submount instance, as the waitcounter is per connection, not per     superblock.

    Revert to using synchronous release requests for the auto_submounts case,which is virtiofs only at this     time. (CVE-2026-53381)

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

    vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write

    A KASAN null-ptr-deref was observed in vcs_notifier():

    BUG: KASAN: null-ptr-deref in vcs_notifier+0x98/0x130Read of size 2 at addr qmp_cmd_name:
    qmp_capabilities, arguments: {}

    The issue is a race condition in vcs_write(). When the console_lock istemporarily dropped (to copy data     from userspace), the vc_data pointerobtained from vcs_vc() may become stale. After re-acquiring the     lock,vcs_vc() is called again to re-validate the pointer. If the vc has beendeallocated in the meantime,     vcs_vc() returns NULL, and the while loopbreaks (with written > 0). However, after the loop,     vcs_scr_updated(vc)is still called with the now-NULL vc pointer, leading to a null pointerdereference in     the notifier chain (vcs_notifier dereferences param->vc).

    Fix this by adding a NULL check for vc before calling vcs_scr_updated(). (CVE-2026-53385)

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

    fuse: re-lock request before replacing page cache folio

    fuse_try_move_folio() unlocks the request on entry but does notre-lock it on the success path. This means     fuse_chan_abort() can end therequest and free the fuse_io_args (eg fuse_readpages_end()) while     thesubsequent copy chain logic after fuse_try_move_folio() accesses thefuse_io_args, leading to use-after-     free issues.

    Fix this by calling lock_request() before replace_page_cache_folio().This ensures the request is locked on     the success path which willprevent the fuse_io_args from being freed while the later copying logicruns,     and also ensures that the ap->folios[i]->mapping is never nullsince ap->folios[i] will always point to the     newfolio afterreplace_page_cache_folio(). (CVE-2026-53388)

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

    net/tcp-ao: fix use-after-free of key in del_async path (CVE-2026-53389)

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

    NFSv4/pNFS: reject zero-length r_addr in nfs4_decode_mp_ds_addr (CVE-2026-53391)

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

    NFSv4/flexfiles: reject zero filehandle version count (CVE-2026-53392)

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

    nfsd: reset write verifier on deferred writeback errors (CVE-2026-53393)

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

    nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race (CVE-2026-53394)

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

    nfsd: fix posix_acl leak on SETACL decode failure (CVE-2026-53397)

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

    i2c: core: fix adapter registration race

    Adapters can be looked up based on their id using i2c_get_adapter()which takes a reference to the embedded     struct device.

    Make sure that the adapter (including its struct device) has beeninitialised before adding it to the IDR     to avoid accessing uninitialiseddata which could, for example, lead to NULL-pointer dereferences oruse-     after-free.

    Note that the i2c-dev chardev, which is registered from a bus notifier,currently uses i2c_get_adapter() so     the adapter needs to be added to theIDR before registration. (CVE-2026-53400)

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

    fbdev: Fix fb_new_modelist to prevent null-ptr-deref in fb_videomode_to_var

    info->var, a framebuffer's current mode, is expected to have a matchingentry in info->modelist.
    var_to_display() relies on this and treats afailed fb_match_mode() as This should not happen.
    fb_set_var() keeps ittrue by adding the mode to the list on every change, anddo_register_framebuffer()     does the same at registration.

    store_modes() replaces the modelist from userspace. fb_new_modelist()validates the new modes but does not     check that info->var still has amatch. It relies on fbcon_new_modelist() to re-point consoles, but     thatonly handles consoles mapped to the framebuffer. With fbcon unbound thereare none, so info->var is     left describing a mode that is no longer in thelist.

    A later console takeover runs var_to_display(), where fb_match_mode()returns NULL and leaves     fb_display[i].mode NULL. fbcon_switch() passes itto display_to_var(), and fb_videomode_to_var()     dereferences the NULL mode.

    Keep the current mode in the list in fb_new_modelist(), the same wayfb_set_var() does. (CVE-2026-53403)

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

    pNFS: Fix use-after-free in pnfs_update_layout() (CVE-2026-63800)

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

    blk-cgroup: fix UAF in __blkcg_rstat_flush() (CVE-2026-63802)

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

    KVM: Replace guest-triggerable BUG_ON() in ioeventfd datamatch with get_unaligned() (CVE-2026-63806)

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

    KVM: x86/mmu: Ensure hugepage is in by slot before checking max mapping level (CVE-2026-63807)

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

    bpf: use kvfree() for replaced sysctl write buffer (CVE-2026-63809)

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

    block: Avoid mounting the bdev pseudo-filesystem in userspace (CVE-2026-63810)

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

    keys: Pin request_key_auth payload in instantiate paths (CVE-2026-63823)

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

    KEYS: fix overflow in keyctl_pkey_params_get_2() (CVE-2026-63824)

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

    fbdev: fix use-after-free in store_modes() (CVE-2026-63826)

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

    apparmor: mediate the implicit connect of TCP fast open sendmsg (CVE-2026-63828)

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

    net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink (CVE-2026-63829)

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.

ID	Name	Product	Family	Published	Updated	Severity
327842	Linux Distros Unpatched Vulnerability : CVE-2026-63806	Nessus	Misc.	7/19/2026	7/25/2026	high
328468	Amazon Linux 2023 : bpftool6.18, kernel6.18, kernel6.18-devel (ALAS2023-2026-1969)	Nessus	Amazon Linux Local Security Checks	7/20/2026	7/31/2026	medium
326038	Photon OS 5.0: Linux PHSA-2026-5.0-0916	Nessus	PhotonOS Local Security Checks	7/9/2026	8/1/2026	high

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