In the Linux kernel, the following vulnerability has been resolved: mm/ksm: fix flag-dropping behavior in ksm_madvise syzkaller discovered the following crash: (kernel BUG) [ 44.607039] ------------[ cut here ]------------ [ 44.607422] kernel BUG at mm/userfaultfd.c:2067! [ 44.608148] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 44.608814] CPU: 1 UID: 0 PID: 2475 Comm: reproducer Not tainted 6.16.0-rc6 #1 PREEMPT(none) [ 44.609635] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 44.610695] RIP: 0010:userfaultfd_release_all+0x3a8/0x460 <snip other registers, drop unreliable trace> [ 44.617726] Call Trace: [ 44.617926] <TASK> [ 44.619284] userfaultfd_release+0xef/0x1b0 [ 44.620976] __fput+0x3f9/0xb60 [ 44.621240] fput_close_sync+0x110/0x210 [ 44.622222] __x64_sys_close+0x8f/0x120 [ 44.622530] do_syscall_64+0x5b/0x2f0 [ 44.622840] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 44.623244] RIP: 0033:0x7f365bb3f227 Kernel panics because it detects UFFD inconsistency during userfaultfd_release_all(). Specifically, a VMA which has a valid pointer to vma->vm_userfaultfd_ctx, but no UFFD flags in vma->vm_flags. The inconsistency is caused in ksm_madvise(): when user calls madvise() with MADV_UNMEARGEABLE on a VMA that is registered for UFFD in MINOR mode, it accidentally clears all flags stored in the upper 32 bits of vma->vm_flags. Assuming x86_64 kernel build, unsigned long is 64-bit and unsigned int and int are 32-bit wide. This setup causes the following mishap during the &= ~VM_MERGEABLE assignment. VM_MERGEABLE is a 32-bit constant of type unsigned int, 0x8000'0000. After ~ is applied, it becomes 0x7fff'ffff unsigned int, which is then promoted to unsigned long before the & operation. This promotion fills upper 32 bits with leading 0s, as we're doing unsigned conversion (and even for a signed conversion, this wouldn't help as the leading bit is 0). & operation thus ends up AND-ing vm_flags with 0x0000'0000'7fff'ffff instead of intended 0xffff'ffff'7fff'ffff and hence accidentally clears the upper 32-bits of its value. Fix it by changing `VM_MERGEABLE` constant to unsigned long, using the BIT() macro. Note: other VM_* flags are not affected: This only happens to the VM_MERGEABLE flag, as the other VM_* flags are all constants of type int and after ~ operation, they end up with leading 1 and are thus converted to unsigned long with leading 1s. Note 2: After commit 31defc3b01d9 ("userfaultfd: remove (VM_)BUG_ON()s"), this is no longer a kernel BUG, but a WARNING at the same place: [ 45.595973] WARNING: CPU: 1 PID: 2474 at mm/userfaultfd.c:2067 but the root-cause (flag-drop) remains the same. [akpm@linux-foundation.org: rust bindgen wasn't able to handle BIT(), from Miguel]

The remote openSUSE 16 host has packages installed that are affected by multiple vulnerabilities as referenced in the openSUSE-SU-2025-20091-1 advisory.

    The SUSE Linux Enterprise 16.0 kernel was updated to fix various security issues

    The following security issues were fixed:

    - CVE-2025-21816: hrtimers: Force migrate away hrtimers queued after (bsc#1238472).
    - CVE-2025-38653: proc: use the same treatment to check proc_lseek as ones for proc_read_iter et.al     (bsc#1248630).
    - CVE-2025-38718: sctp: linearize cloned gso packets in sctp_rcv (bsc#1249161).
    - CVE-2025-39676: scsi: qla4xxx: Prevent a potential error pointer dereference (bsc#1249302).
    - CVE-2025-39702: ipv6: sr: Fix MAC comparison to be constant-time (bsc#1249317).
    - CVE-2025-39756: fs: Prevent file descriptor table allocations exceeding INT_MAX (bsc#1249512).
    - CVE-2025-39779: btrfs: subpage: keep TOWRITE tag until folio is cleaned (bsc#1249495).
    - CVE-2025-39812: sctp: initialize more fields in sctp_v6_from_sk() (bsc#1250202).
    - CVE-2025-39866: fs: writeback: fix use-after-free in __mark_inode_dirty() (bsc#1250455).
    - CVE-2025-39876: net: fec: Fix possible NPD in fec_enet_phy_reset_after_clk_enable() (bsc#1250400).
    - CVE-2025-39881: kernfs: Fix UAF in polling when open file is released (bsc#1250379).
    - CVE-2025-39895: sched: Fix sched_numa_find_nth_cpu() if mask offline (bsc#1250721).
    - CVE-2025-39903: of_numa: fix uninitialized memory nodes causing kernel panic (bsc#1250749).
    - CVE-2025-39911: i40e: fix IRQ freeing in i40e_vsi_request_irq_msix error path (bsc#1250704).
    - CVE-2025-39947: net/mlx5e: Harden uplink netdev access against device unbind (bsc#1251232).
    - CVE-2025-39948: ice: fix Rx page leak on multi-buffer frames (bsc#1251233).
    - CVE-2025-39949: qed: Don't collect too many protection override GRC elements (bsc#1251177).
    - CVE-2025-39950: net/tcp: Fix a NULL pointer dereference when using TCP-AO with TCP_REPAIR (bsc#1251176).
    - CVE-2025-39955: tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect() (bsc#1251804).
    - CVE-2025-39956: igc: don't fail igc_probe() on LED setup error (bsc#1251809).
    - CVE-2025-39963: io_uring: fix incorrect io_kiocb reference in io_link_skb (bsc#1251819).
    - CVE-2025-39968: i40e: add max boundary check for VF filters (bsc#1252047).
    - CVE-2025-39969: i40e: fix validation of VF state in get resources (bsc#1252044).
    - CVE-2025-39970: i40e: fix input validation logic for action_meta (bsc#1252051).
    - CVE-2025-39971: i40e: fix idx validation in config queues msg (bsc#1252052).
    - CVE-2025-39972: i40e: fix idx validation in i40e_validate_queue_map (bsc#1252039).
    - CVE-2025-39973: i40e: add validation for ring_len param (bsc#1252035).
    - CVE-2025-39978: octeontx2-pf: Fix potential use after free in otx2_tc_add_flow() (bsc#1252069).
    - CVE-2025-39979: net/mlx5: fs, add API for sharing HWS action by refcount (bsc#1252067).
    - CVE-2025-39984: net: tun: Update napi->skb after XDP process (bsc#1252081).
    - CVE-2025-39992: mm: swap: check for stable address space before operating on the VMA (bsc#1252076).
    - CVE-2025-40000: wifi: rtw89: fix use-after-free in rtw89_core_tx_kick_off_and_wait() (bsc#1252062).
    - CVE-2025-40005: spi: cadence-quadspi: Implement refcount to handle unbind during busy (bsc#1252349).
    - CVE-2025-40012: net/smc: fix warning in smc_rx_splice() when calling get_page() (bsc#1252330).
    - CVE-2025-40018: ipvs: Defer ip_vs_ftp unregister during netns cleanup (bsc#1252688).
    - CVE-2025-40040: mm/ksm: fix flag-dropping behavior in ksm_madvise (bsc#1252780).
    - CVE-2025-40051: vhost: vringh: Modify the return value check (bsc#1252858).
    - CVE-2025-40056: vhost: vringh: Fix copy_to_iter return value check (bsc#1252826).
    - CVE-2025-40060: coresight: trbe: Return NULL pointer for allocation failures (bsc#1252848).
    - CVE-2025-40078: bpf: Explicitly check accesses to bpf_sock_addr (bsc#1252789).
    - CVE-2025-40080: nbd: restrict sockets to TCP and UDP (bsc#1252774).
    - CVE-2025-40100: btrfs: do not assert we found block group item when creating free space tree     (bsc#1252918).

    The following non security issues were fixed:

    - add bug reference to existing hv_netvsc change (bsc#1252265)
    - amd-pstate-ut: Reset amd-pstate driver mode after running selftests (bsc#1249226).
    - cgroup/cpuset: Remove remote_partition_check() & make update_cpumasks_hier() handle remote partition     (bsc#1241166).
    - cpuset: Use new excpus for nocpu error check when enabling root partition (bsc#1241166).
    - cpuset: fix failure to enable isolated partition when containing isolcpus (bsc#1241166).
    - doc/README.SUSE: Correct the character used for TAINT_NO_SUPPORT       The character was previously 'N', but upstream used it for TAINT_TEST,       which prompted the change of TAINT_NO_SUPPORT to 'n'.
    - dpll: zl3073x: Add firmware loading functionality (bsc#1252253).
    - dpll: zl3073x: Add functions to access hardware registers (bsc#1252253).
    - dpll: zl3073x: Add low-level flash functions (bsc#1252253).
    - dpll: zl3073x: Add support to get fractional frequency offset (bsc#1252253).
    - dpll: zl3073x: Add support to get phase offset on connected input pin (bsc#1252253).
    - dpll: zl3073x: Add support to get/set esync on pins (bsc#1252253).
    - dpll: zl3073x: Fix double free in zl3073x_devlink_flash_update() (bsc#1252253).
    - dpll: zl3073x: Handle missing or corrupted flash configuration (bsc#1252253).
    - dpll: zl3073x: Implement devlink flash callback (bsc#1252253).
    - dpll: zl3073x: Increase maximum size of flash utility (bsc#1252253).
    - dpll: zl3073x: Refactor DPLL initialization (bsc#1252253).
    - drm/amd/pm: fix smu table id bound check issue in smu_cmn_update_table() (git-fixes).
    - drm/xe/guc: Prepare GuC register list and update ADS size for error capture (stable-fixes).
    - ixgbe: handle IXGBE_VF_FEATURES_NEGOTIATE mbox cmd (bsc#1247222).
    - ixgbe: handle IXGBE_VF_GET_PF_LINK_STATE mailbox operation (bsc#1247222).
    - ixgbevf: fix getting link speed data for E610 devices (bsc#1247222).
    - ixgbevf: fix mailbox API compatibility by negotiating supported features (bsc#1247222).
    - kbuild/modfinal: Link livepatches with module-common.o (bsc#1218644, bsc#1252270).
    - kdb: Replace deprecated strcpy() with memmove() in vkdb_printf() (bsc#1252939).
    - kernel-subpackage-spec: Do not doubly-sign modules (bsc#1251930).
    - nvme-auth: update sc_c in host response (git-fixes bsc#1249397).
    - perf hwmon_pmu: Fix uninitialized variable warning (perf-sle16-v6.13-userspace-update, git-fixes).
    - phy: cadence: cdns-dphy: Update calibration wait time for startup state machine (git-fixes).
    - powerpc/fadump: skip parameter area allocation when fadump is disabled (jsc#PED-9891 git-fixes).
    - proc: fix missing pde_set_flags() for net proc files (bsc#1248630)
    - proc: fix type confusion in pde_set_flags() (bsc#1248630)
    - rpm/check-for-config-changes: ignore CONFIG_SCHED_PROXY_EXEC, too (bsc#1250946)
    - scsi: storvsc: Prefer returning channel with the same CPU as on the I/O issuing CPU (bsc#1252267).
    - x86/microcode/AMD: Limit Entrysign signature checking to known generations (bsc#1252725).
    - x86/resctrl: Fix miscount of bandwidth event when reactivating previously unavailable RMID     (bsc#1252734).
    - x86/resctrl: Refactor resctrl_arch_rmid_read() (bsc#1252734).
    - x86/virt/tdx: Mark memory cache state incoherent when making SEAMCALL (jsc#PED-348).

Tenable has extracted the preceding description block directly from the SUSE 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 11 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-4379 advisory.

    -------------------------------------------------------------------------     Debian LTS Advisory DLA-4379-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/                        Ben Hutchings     November 25, 2025                             https://wiki.debian.org/LTS
    -------------------------------------------------------------------------

    Package        : linux-6.1     Version        : 6.1.158-1~deb11u1     CVE ID         : CVE-2025-21861 CVE-2025-39929 CVE-2025-39931 CVE-2025-39934                      CVE-2025-39937 CVE-2025-39938 CVE-2025-39942 CVE-2025-39943                      CVE-2025-39944 CVE-2025-39945 CVE-2025-39946 CVE-2025-39949                      CVE-2025-39951 CVE-2025-39953 CVE-2025-39955 CVE-2025-39957                      CVE-2025-39964 CVE-2025-39967 CVE-2025-39968 CVE-2025-39969                      CVE-2025-39970 CVE-2025-39971 CVE-2025-39972 CVE-2025-39973                      CVE-2025-39977 CVE-2025-39978 CVE-2025-39980 CVE-2025-39982                      CVE-2025-39985 CVE-2025-39986 CVE-2025-39987 CVE-2025-39988                      CVE-2025-39993 CVE-2025-39994 CVE-2025-39995 CVE-2025-39996                      CVE-2025-39998 CVE-2025-40001 CVE-2025-40006 CVE-2025-40008                      CVE-2025-40010 CVE-2025-40011 CVE-2025-40013 CVE-2025-40018                      CVE-2025-40019 CVE-2025-40020 CVE-2025-40021 CVE-2025-40022                      CVE-2025-40026 CVE-2025-40027 CVE-2025-40029 CVE-2025-40030                      CVE-2025-40032 CVE-2025-40035 CVE-2025-40036 CVE-2025-40040                      CVE-2025-40042 CVE-2025-40043 CVE-2025-40044 CVE-2025-40048                      CVE-2025-40049 CVE-2025-40051 CVE-2025-40053 CVE-2025-40055                      CVE-2025-40056 CVE-2025-40060 CVE-2025-40062 CVE-2025-40068                      CVE-2025-40070 CVE-2025-40078 CVE-2025-40080 CVE-2025-40081                      CVE-2025-40084 CVE-2025-40085 CVE-2025-40087 CVE-2025-40088                      CVE-2025-40092 CVE-2025-40093 CVE-2025-40094 CVE-2025-40095                      CVE-2025-40096 CVE-2025-40099 CVE-2025-40100 CVE-2025-40103                      CVE-2025-40104 CVE-2025-40105 CVE-2025-40106 CVE-2025-40107                      CVE-2025-40109 CVE-2025-40111 CVE-2025-40112 CVE-2025-40115                      CVE-2025-40116 CVE-2025-40118 CVE-2025-40120 CVE-2025-40121                      CVE-2025-40123 CVE-2025-40124 CVE-2025-40125 CVE-2025-40126                      CVE-2025-40127 CVE-2025-40134 CVE-2025-40140 CVE-2025-40141                      CVE-2025-40153 CVE-2025-40154 CVE-2025-40156 CVE-2025-40167                      CVE-2025-40171 CVE-2025-40173 CVE-2025-40176 CVE-2025-40178                      CVE-2025-40179 CVE-2025-40183 CVE-2025-40186 CVE-2025-40187                      CVE-2025-40188 CVE-2025-40190 CVE-2025-40193 CVE-2025-40194                      CVE-2025-40197 CVE-2025-40198 CVE-2025-40200 CVE-2025-40201                      CVE-2025-40202 CVE-2025-40204 CVE-2025-40205 CVE-2025-40207

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

    For Debian 11 bullseye, these problems have been fixed in version     6.1.158-1~deb11u1.  This version additionally includes many more bug     fixes from stable updates 6.1.154-6.1.158.

    We recommend that you upgrade your linux-6.1 packages.

    For the detailed security status of linux-6.1 please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/linux-6.1

    Further information about Debian LTS security advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://wiki.debian.org/LTS     Attachment:
    signature.asc     Description: PGP signature

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.

An update of the linux package has been released.

The remote Debian 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6053 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6053-1                   security@debian.org     https://www.debian.org/security/                     Salvatore Bonaccorso     November 11, 2025                     https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : linux     CVE ID         : CVE-2025-21861 CVE-2025-39929 CVE-2025-39931 CVE-2025-39934                      CVE-2025-39937 CVE-2025-39938 CVE-2025-39942 CVE-2025-39943                      CVE-2025-39944 CVE-2025-39945 CVE-2025-39946 CVE-2025-39949                      CVE-2025-39951 CVE-2025-39953 CVE-2025-39955 CVE-2025-39957                      CVE-2025-39964 CVE-2025-39967 CVE-2025-39968 CVE-2025-39969                      CVE-2025-39970 CVE-2025-39971 CVE-2025-39972 CVE-2025-39973                      CVE-2025-39977 CVE-2025-39978 CVE-2025-39980 CVE-2025-39982                      CVE-2025-39985 CVE-2025-39986 CVE-2025-39987 CVE-2025-39988                      CVE-2025-39993 CVE-2025-39994 CVE-2025-39995 CVE-2025-39996                      CVE-2025-39998 CVE-2025-40001 CVE-2025-40006 CVE-2025-40008                      CVE-2025-40010 CVE-2025-40011 CVE-2025-40013 CVE-2025-40018                      CVE-2025-40019 CVE-2025-40020 CVE-2025-40021 CVE-2025-40022                      CVE-2025-40026 CVE-2025-40027 CVE-2025-40029 CVE-2025-40030                      CVE-2025-40032 CVE-2025-40035 CVE-2025-40036 CVE-2025-40040                      CVE-2025-40042 CVE-2025-40043 CVE-2025-40044 CVE-2025-40048                      CVE-2025-40049 CVE-2025-40051 CVE-2025-40053 CVE-2025-40055                      CVE-2025-40056 CVE-2025-40060 CVE-2025-40062 CVE-2025-40068                      CVE-2025-40070 CVE-2025-40078 CVE-2025-40080 CVE-2025-40081                      CVE-2025-40084 CVE-2025-40085 CVE-2025-40087 CVE-2025-40088                      CVE-2025-40092 CVE-2025-40093 CVE-2025-40094 CVE-2025-40095                      CVE-2025-40096 CVE-2025-40099 CVE-2025-40100 CVE-2025-40103                      CVE-2025-40104 CVE-2025-40105 CVE-2025-40106 CVE-2025-40107                      CVE-2025-40109

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

    For the oldstable distribution (bookworm), these problems have been fixed     in version 6.1.158-1.

    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.

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

  - mm/ksm: fix flag-dropping behavior in ksm_madvise syzkaller discovered the following crash: (kernel BUG) [     44.607039] ------------[ cut here ]------------ [ 44.607422] kernel BUG at mm/userfaultfd.c:2067! [     44.608148] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI [ 44.608814] CPU: 1 UID: 0 PID:
    2475 Comm: reproducer Not tainted 6.16.0-rc6 #1 PREEMPT(none) [ 44.609635] Hardware name: QEMU Standard PC     (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 44.610695] RIP:
    0010:userfaultfd_release_all+0x3a8/0x460 <snip other registers, drop unreliable trace> [ 44.617726] Call     Trace: [ 44.617926] <TASK> [ 44.619284] userfaultfd_release+0xef/0x1b0 [ 44.620976] __fput+0x3f9/0xb60 [     44.621240] fput_close_sync+0x110/0x210 [ 44.622222] __x64_sys_close+0x8f/0x120 [ 44.622530]     do_syscall_64+0x5b/0x2f0 [ 44.622840] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 44.623244] RIP:
    0033:0x7f365bb3f227 Kernel panics because it detects UFFD inconsistency during userfaultfd_release_all().
    Specifically, a VMA which has a valid pointer to vma->vm_userfaultfd_ctx, but no UFFD flags in     vma->vm_flags. The inconsistency is caused in ksm_madvise(): when user calls madvise() with     MADV_UNMEARGEABLE on a VMA that is registered for UFFD in MINOR mode, it accidentally clears all flags     stored in the upper 32 bits of vma->vm_flags. Assuming x86_64 kernel build, unsigned long is 64-bit and     unsigned int and int are 32-bit wide. This setup causes the following mishap during the &= ~VM_MERGEABLE     assignment. VM_MERGEABLE is a 32-bit constant of type unsigned int, 0x8000'0000. After ~ is applied, it     becomes 0x7fff'ffff unsigned int, which is then promoted to unsigned long before the & operation. This     promotion fills upper 32 bits with leading 0s, as we're doing unsigned conversion (and even for a signed     conversion, this wouldn't help as the leading bit is 0). & operation thus ends up AND-ing vm_flags with     0x0000'0000'7fff'ffff instead of intended 0xffff'ffff'7fff'ffff and hence accidentally clears the upper     32-bits of its value. Fix it by changing `VM_MERGEABLE` constant to unsigned long, using the BIT() macro.
    Note: other VM_* flags are not affected: This only happens to the VM_MERGEABLE flag, as the other VM_*     flags are all constants of type int and after ~ operation, they end up with leading 1 and are thus     converted to unsigned long with leading 1s. Note 2: After commit 31defc3b01d9 (userfaultfd: remove     (VM_)BUG_ON()s), this is no longer a kernel BUG, but a WARNING at the same place: [ 45.595973] WARNING:
    CPU: 1 PID: 2474 at mm/userfaultfd.c:2067 but the root-cause (flag-drop) remains the same. [akpm@linux-     foundation.org: rust bindgen wasn't able to handle BIT(), from Miguel] (CVE-2025-40040)

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

ID	Name	Product	Family	Severity
277016	openSUSE 16 Security Update : kernel (openSUSE-SU-2025-20091-1)	Nessus	SuSE Local Security Checks	high
276782	Debian dla-4379 : linux-config-6.1 - security update	Nessus	Debian Local Security Checks	medium
275495	Photon OS 5.0: Linux PHSA-2025-5.0-0677	Nessus	PhotonOS Local Security Checks	medium
274816	Debian dsa-6053 : affs-modules-6.1.0-37-4kc-malta-di - security update	Nessus	Debian Local Security Checks	medium
271902	Linux Distros Unpatched Vulnerability : CVE-2025-40040	Nessus	Misc.	medium

Detections

Analytics

CVE-2025-40040

medium

Tenable Plugins

high

medium

medium

medium

medium