In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Load DR6 with guest value only before entering .vcpu_run() loop Move the conditional loading of hardware DR6 with the guest's DR6 value out of the core .vcpu_run() loop to fix a bug where KVM can load hardware with a stale vcpu->arch.dr6. When the guest accesses a DR and host userspace isn't debugging the guest, KVM disables DR interception and loads the guest's values into hardware on VM-Enter and saves them on VM-Exit. This allows the guest to access DRs at will, e.g. so that a sequence of DR accesses to configure a breakpoint only generates one VM-Exit. For DR0-DR3, the logic/behavior is identical between VMX and SVM, and also identical between KVM_DEBUGREG_BP_ENABLED (userspace debugging the guest) and KVM_DEBUGREG_WONT_EXIT (guest using DRs), and so KVM handles loading DR0-DR3 in common code, _outside_ of the core kvm_x86_ops.vcpu_run() loop. But for DR6, the guest's value doesn't need to be loaded into hardware for KVM_DEBUGREG_BP_ENABLED, and SVM provides a dedicated VMCB field whereas VMX requires software to manually load the guest value, and so loading the guest's value into DR6 is handled by {svm,vmx}_vcpu_run(), i.e. is done _inside_ the core run loop. Unfortunately, saving the guest values on VM-Exit is initiated by common x86, again outside of the core run loop. If the guest modifies DR6 (in hardware, when DR interception is disabled), and then the next VM-Exit is a fastpath VM-Exit, KVM will reload hardware DR6 with vcpu->arch.dr6 and clobber the guest's actual value. The bug shows up primarily with nested VMX because KVM handles the VMX preemption timer in the fastpath, and the window between hardware DR6 being modified (in guest context) and DR6 being read by guest software is orders of magnitude larger in a nested setup. E.g. in non-nested, the VMX preemption timer would need to fire precisely between #DB injection and the #DB handler's read of DR6, whereas with a KVM-on-KVM setup, the window where hardware DR6 is "dirty" extends all the way from L1 writing DR6 to VMRESUME (in L1). L1's view: ========== <L1 disables DR interception> CPU 0/KVM-7289 [023] d.... 2925.640961: kvm_entry: vcpu 0 A: L1 Writes DR6 CPU 0/KVM-7289 [023] d.... 2925.640963: <hack>: Set DRs, DR6 = 0xffff0ff1 B: CPU 0/KVM-7289 [023] d.... 2925.640967: kvm_exit: vcpu 0 reason EXTERNAL_INTERRUPT intr_info 0x800000ec D: L1 reads DR6, arch.dr6 = 0 CPU 0/KVM-7289 [023] d.... 2925.640969: <hack>: Sync DRs, DR6 = 0xffff0ff0 CPU 0/KVM-7289 [023] d.... 2925.640976: kvm_entry: vcpu 0 L2 reads DR6, L1 disables DR interception CPU 0/KVM-7289 [023] d.... 2925.640980: kvm_exit: vcpu 0 reason DR_ACCESS info1 0x0000000000000216 CPU 0/KVM-7289 [023] d.... 2925.640983: kvm_entry: vcpu 0 CPU 0/KVM-7289 [023] d.... 2925.640983: <hack>: Set DRs, DR6 = 0xffff0ff0 L2 detects failure CPU 0/KVM-7289 [023] d.... 2925.640987: kvm_exit: vcpu 0 reason HLT L1 reads DR6 (confirms failure) CPU 0/KVM-7289 [023] d.... 2925.640990: <hack>: Sync DRs, DR6 = 0xffff0ff0 L0's view: ========== L2 reads DR6, arch.dr6 = 0 CPU 23/KVM-5046 [001] d.... 3410.005610: kvm_exit: vcpu 23 reason DR_ACCESS info1 0x0000000000000216 CPU 23/KVM-5046 [001] ..... 3410.005610: kvm_nested_vmexit: vcpu 23 reason DR_ACCESS info1 0x0000000000000216 L2 => L1 nested VM-Exit CPU 23/KVM-5046 [001] ..... 3410.005610: kvm_nested_vmexit_inject: reason: DR_ACCESS ext_inf1: 0x0000000000000216 CPU 23/KVM-5046 [001] d.... 3410.005610: kvm_entry: vcpu 23 CPU 23/KVM-5046 [001] d.... 3410.005611: kvm_exit: vcpu 23 reason VMREAD CPU 23/KVM-5046 [001] d.... 3410.005611: kvm_entry: vcpu 23 CPU 23/KVM-5046 [001] d.... 3410. ---truncated---

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.

The remote SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2025:01620-1 advisory.

    The SUSE Linux Enterprise 15 SP5 kernel was updated to receive various security bugfixes.


    The following security bugs were fixed:

    - CVE-2022-48933: netfilter: nf_tables: fix memory leak during stateful obj update (bsc#1229621).
    - CVE-2022-49110: netfilter: conntrack: revisit gc autotuning (bsc#1237981).
    - CVE-2022-49139: Bluetooth: fix null ptr deref on hci_sync_conn_complete_evt (bsc#1238032).
    - CVE-2022-49767: 9p/trans_fd: always use O_NONBLOCK read/write (bsc#1242493).
    - CVE-2024-46763: fou: Fix null-ptr-deref in GRO (bsc#1230764).
    - CVE-2024-50038: netfilter: xtables: avoid NFPROTO_UNSPEC where needed (bsc#1231910).
    - CVE-2025-21726: padata: avoid UAF for reorder_work (bsc#1238865).
    - CVE-2025-21785: arm64: cacheinfo: Avoid out-of-bounds write to cacheinfo array (bsc#1238747).
    - CVE-2025-21791: vrf: use RCU protection in l3mdev_l3_out() (bsc#1238512).
    - CVE-2025-21812: ax25: rcu protect dev->ax25_ptr (bsc#1238471).
    - CVE-2025-21839: KVM: x86: Load DR6 with guest value only before entering .vcpu_run() loop (bsc#1239061).
    - CVE-2025-22004: net: atm: fix use after free in lec_send() (bsc#1240835).
    - CVE-2025-22020: memstick: rtsx_usb_ms: Fix slab-use-after-free in rtsx_usb_ms_drv_remove (bsc#1241280).
    - CVE-2025-22045: x86/mm: Fix flush_tlb_range() when used for zapping normal PMDs (bsc#1241433).
    - CVE-2025-22055: net: fix geneve_opt length integer overflow (bsc#1241371).
    - CVE-2025-22097: drm/vkms: Fix use after free and double free on init error (bsc#1241541).
    - CVE-2025-2312: CIFS: New mount option for cifs.upcall namespace resolution (bsc#1239684).
    - CVE-2025-23138: watch_queue: fix pipe accounting mismatch (bsc#1241648).
    - CVE-2025-39735: jfs: fix slab-out-of-bounds read in ea_get() (bsc#1241625).


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 Ubuntu 24.04 LTS / 24.10 host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-7521-1 advisory.

    Several security issues were discovered in the Linux kernel. An attacker could possibly use these to     compromise the system. This update corrects flaws in the following subsystems:

    - ARM64 architecture;

    - PowerPC architecture;

    - x86 architecture;

    - Block layer subsystem;

    - Serial ATA and Parallel ATA drivers;

    - Drivers core;

    - Network block device driver;

    - Bluetooth drivers;

    - Character device driver;

    - TPM device driver;

    - Clock framework and drivers;

    - Hardware crypto device drivers;

    - FireWire subsystem;

    - EFI core;

    - Qualcomm firmware drivers;

    - GPIO subsystem;

    - GPU drivers;

    - HID subsystem;

    - I2C subsystem;

    - I3C subsystem;

    - InfiniBand drivers;

    - Input Device (Mouse) drivers;

    - IOMMU subsystem;

    - Multiple devices driver;

    - Media drivers;

    - NVIDIA Tegra memory controller driver;

    - Fastrpc Driver;

    - Network drivers;

    - Operating Performance Points (OPP) driver;

    - PCI subsystem;

    - x86 platform drivers;

    - PPS (Pulse Per Second) driver;

    - PTP clock framework;

    - Remote Processor subsystem;

    - Real Time Clock drivers;

    - S/390 drivers;

    - SCSI subsystem;

    - QCOM SoC drivers;

    - SPI subsystem;

    - Media staging drivers;

    - Trusted Execution Environment drivers;

    - TTY drivers;

    - UFS subsystem;

    - USB Device Class drivers;

    - USB core drivers;

    - USB Gadget drivers;

    - USB Host Controller drivers;

    - Framebuffer layer;

    - File systems infrastructure;

    - BTRFS file system;

    - Ceph distributed file system;

    - Network file system (NFS) client;

    - Network file system (NFS) server daemon;

    - NILFS2 file system;

    - Overlay file system;

    - SMB network file system;

    - UBI file system;

    - BPF subsystem;

    - Timer subsystem;

    - KVM subsystem;

    - Networking core;

    - ptr_ring data structure definitions;

    - Networking subsytem;

    - Amateur Radio drivers;

    - L3 Master device support module;

    - TCP network protocol;

    - XFRM subsystem;

    - Tracing infrastructure;

    - io_uring subsystem;

    - Process Accounting mechanism;

    - Perf events;

    - Padata parallel execution mechanism;

    - printk logging mechanism;

    - Scheduler infrastructure;

    - Workqueue subsystem;

    - Memory management;

    - B.A.T.M.A.N. meshing protocol;

    - Bluetooth subsystem;

    - IPv4 networking;

    - IPv6 networking;

    - MAC80211 subsystem;

    - Multipath TCP;

    - Netfilter;

    - NFC subsystem;

    - Open vSwitch;

    - Rose network layer;

    - RxRPC session sockets;

    - Network traffic control;

    - Wireless networking;

    - Key management;

    - Landlock security;

    - Linux Security Modules (LSM) Framework;

    - Tomoyo security module;

    - SoC audio core drivers;

    - SOF drivers; (CVE-2025-21737, CVE-2025-21711, CVE-2025-21987, CVE-2025-21848, CVE-2024-49570,     CVE-2025-21762, CVE-2025-21738, CVE-2025-21712, CVE-2025-21719, CVE-2025-21870, CVE-2024-57984,     CVE-2025-21815, CVE-2025-21744, CVE-2024-58058, CVE-2024-58078, CVE-2024-57990, CVE-2024-54458,     CVE-2025-21899, CVE-2025-21814, CVE-2025-21746, CVE-2024-54456, CVE-2025-21739, CVE-2024-58057,     CVE-2025-21855, CVE-2025-21758, CVE-2024-58006, CVE-2024-58007, CVE-2025-21720, CVE-2024-58090,     CVE-2025-21852, CVE-2024-57982, CVE-2024-58013, CVE-2024-58082, CVE-2025-21825, CVE-2024-58072,     CVE-2024-57996, CVE-2025-21787, CVE-2025-21742, CVE-2025-21705, CVE-2025-21829, CVE-2024-58060,     CVE-2025-21811, CVE-2025-21900, CVE-2025-21853, CVE-2025-21809, CVE-2025-21938, CVE-2025-21728,     CVE-2025-21785, CVE-2025-21732, CVE-2025-21888, CVE-2025-21768, CVE-2025-21875, CVE-2025-21721,     CVE-2025-21766, CVE-2025-21892, CVE-2024-57953, CVE-2025-21772, CVE-2025-21735, CVE-2024-58017,     CVE-2024-58086, CVE-2024-58084, CVE-2025-21761, CVE-2024-58008, CVE-2024-57988, CVE-2025-21874,     CVE-2024-58011, CVE-2025-21706, CVE-2024-57999, CVE-2025-21858, CVE-2024-58061, CVE-2025-21727,     CVE-2025-21780, CVE-2024-58051, CVE-2025-21791, CVE-2025-21788, CVE-2025-21786, CVE-2024-58012,     CVE-2024-58010, CVE-2024-58001, CVE-2025-21844, CVE-2025-21708, CVE-2024-57834, CVE-2025-21873,     CVE-2025-21704, CVE-2025-21765, CVE-2025-21839, CVE-2025-21723, CVE-2024-57974, CVE-2025-21876,     CVE-2025-21782, CVE-2025-21866, CVE-2024-58076, CVE-2025-21724, CVE-2025-21895, CVE-2025-21770,     CVE-2025-21835, CVE-2024-58052, CVE-2025-21827, CVE-2024-58069, CVE-2025-21828, CVE-2025-21734,     CVE-2025-21781, CVE-2025-21971, CVE-2025-21775, CVE-2024-52559, CVE-2024-58020, CVE-2025-21713,     CVE-2024-58068, CVE-2024-58018, CVE-2025-21806, CVE-2025-21802, CVE-2025-21731, CVE-2025-21741,     CVE-2025-21847, CVE-2025-21767, CVE-2024-58003, CVE-2024-57993, CVE-2025-21725, CVE-2025-21796,     CVE-2025-21764, CVE-2025-21862, CVE-2025-21733, CVE-2024-58075, CVE-2025-21808, CVE-2024-58034,     CVE-2025-21707, CVE-2024-58080, CVE-2025-21784, CVE-2024-57994, CVE-2025-21890, CVE-2025-21754,     CVE-2024-58063, CVE-2025-21826, CVE-2025-21821, CVE-2024-58079, CVE-2024-58056, CVE-2025-21798,     CVE-2024-58077, CVE-2024-58019, CVE-2025-21748, CVE-2025-21759, CVE-2024-58004, CVE-2024-58081,     CVE-2024-57978, CVE-2025-21865, CVE-2024-58002, CVE-2025-21810, CVE-2025-21743, CVE-2024-57989,     CVE-2025-21718, CVE-2024-57987, CVE-2025-21877, CVE-2024-57973, CVE-2024-58070, CVE-2024-58071,     CVE-2025-21891, CVE-2024-58021, CVE-2024-58016, CVE-2024-58005, CVE-2025-21760, CVE-2025-21883,     CVE-2025-21878, CVE-2025-21881, CVE-2025-21838, CVE-2025-21783, CVE-2024-57986, CVE-2025-21793,     CVE-2025-21859, CVE-2025-21792, CVE-2025-21820, CVE-2025-21799, CVE-2025-21750, CVE-2025-21795,     CVE-2025-21854, CVE-2025-21836, CVE-2025-21726, CVE-2025-21846, CVE-2025-21864, CVE-2024-57977,     CVE-2025-21887, CVE-2025-21710, CVE-2025-21889, CVE-2025-21812, CVE-2025-21773, CVE-2024-57852,     CVE-2025-21856, CVE-2025-21871, CVE-2025-21763, CVE-2024-58064, CVE-2025-21804, CVE-2024-58055,     CVE-2025-21898, CVE-2025-21776, CVE-2025-21869, CVE-2025-21745, CVE-2025-21736, CVE-2025-21716,     CVE-2024-57981, CVE-2024-57979, CVE-2025-21715, CVE-2024-57998, CVE-2025-21790, CVE-2024-58085,     CVE-2025-21749, CVE-2024-58088, CVE-2025-21753, CVE-2025-21851, CVE-2024-58054, CVE-2025-21830,     CVE-2025-21832, CVE-2024-57980, CVE-2025-21885, CVE-2025-21863, CVE-2024-58053, CVE-2025-21823,     CVE-2025-21857, CVE-2024-58083, CVE-2024-58014, CVE-2025-21816, CVE-2025-21779, CVE-2025-21872,     CVE-2024-57997, CVE-2025-21867, CVE-2024-57985, CVE-2025-21831, CVE-2025-21801, CVE-2025-21868,     CVE-2025-21849)

Tenable has extracted the preceding description block directly from the Ubuntu 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 SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2025:1195-1 advisory.

    The SUSE Linux Enterprise 15 SP4 kernel was updated to receive various security bugfixes.

    The following security bugs were fixed:

    - CVE-2022-49053: scsi: target: tcmu: Fix possible page UAF (bsc#1237918).
    - CVE-2022-49465: blk-throttle: Set BIO_THROTTLED when bio has been throttled (bsc#1238919).
    - CVE-2022-49739: gfs2: Always check inode size of inline inodes (bsc#1240207).
    - CVE-2023-52935: mm/khugepaged: fix ->anon_vma race (bsc#1240276).
    - CVE-2024-53064: idpf: fix idpf_vc_core_init error path (bsc#1233558 bsc#1234464).
    - CVE-2024-56651: can: hi311x: hi3110_can_ist(): fix potential use-after-free (bsc#1235528).
    - CVE-2024-58083: KVM: Explicitly verify target vCPU is online in kvm_get_vcpu() (bsc#1239036).
    - CVE-2025-21693: mm: zswap: properly synchronize freeing resources during CPU hotunplug (bsc#1237029).
    - CVE-2025-21714: RDMA/mlx5: Fix implicit ODP use after free (bsc#1237890).
    - CVE-2025-21732: RDMA/mlx5: Fix a race for an ODP MR which leads to CQE with error (bsc#1237877).
    - CVE-2025-21753: btrfs: fix use-after-free when attempting to join an aborted transaction (bsc#1237875).
    - CVE-2025-21772: partitions: mac: fix handling of bogus partition table (bsc#1238911).


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.

ID	Name	Product	Family	Severity
237223	Debian dsa-5925 : affs-modules-6.1.0-33-4kc-malta-di - security update	Nessus	Debian Local Security Checks	medium
237098	SUSE SLES15 Security Update : kernel (SUSE-SU-2025:01620-1)	Nessus	SuSE Local Security Checks	high
236983	Ubuntu 24.04 LTS / 24.10 : Linux kernel vulnerabilities (USN-7521-1)	Nessus	Ubuntu Local Security Checks	high
236949	Photon OS 5.0: Linux PHSA-2025-5.0-0521	Nessus	PhotonOS Local Security Checks	medium
234182	SUSE SLES15 Security Update : kernel (SUSE-SU-2025:1195-1)	Nessus	SuSE Local Security Checks	high

Detections

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CVE-2025-21839

medium

Tenable Plugins

medium

high

high

medium

high