In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: ensure safe access to master conntrack Holding reference on the expectation is not sufficient, the master conntrack object can just go away, making exp->master invalid. To access exp->master safely: - Grab the nf_conntrack_expect_lock, this gets serialized with clean_from_lists() which also holds this lock when the master conntrack goes away. - Hold reference on master conntrack via nf_conntrack_find_get(). Not so easy since the master tuple to look up for the master conntrack is not available in the existing problematic paths. This patch goes for extending the nf_conntrack_expect_lock section to address this issue for simplicity, in the cases that are described below this is just slightly extending the lock section. The add expectation command already holds a reference to the master conntrack from ctnetlink_create_expect(). However, the delete expectation command needs to grab the spinlock before looking up for the expectation. Expand the existing spinlock section to address this to cover the expectation lookup. Note that, the nf_ct_expect_iterate_net() calls already grabs the spinlock while iterating over the expectation table, which is correct. The get expectation command needs to grab the spinlock to ensure master conntrack does not go away. This also expands the existing spinlock section to cover the expectation lookup too. I needed to move the netlink skb allocation out of the spinlock to keep it GFP_KERNEL. For the expectation events, the IPEXP_DESTROY event is already delivered under the spinlock, just move the delivery of IPEXP_NEW under the spinlock too because the master conntrack event cache is reached through exp->master. While at it, add lockdep notations to help identify what codepaths need to grab the spinlock.

The remote Redhat Enterprise Linux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:21557 advisory.

    The kernel packages contain the Linux kernel, the core of any Linux operating system.

    Security Fix(es):

    * kernel: can: j1939: j1939_session_new(): fix skb reference counting (CVE-2024-56645)

    * kernel: ima: don't clear IMA_DIGSIG flag when setting or removing non-IMA xattr (CVE-2025-68183)

    * kernel: mm: thp: deny THP for files on anonymous inodes (CVE-2026-23375)

    * kernel: netfilter: nf_tables: release flowtable after rcu grace period on error (CVE-2026-23392)

    * kernel: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() (CVE-2026-23455)

    * kernel: net: sched: act_csum: validate nested VLAN headers (CVE-2026-31684)

    * kernel: netfilter: ip6t_eui64: reject invalid MAC header for all packets (CVE-2026-31685)

    * kernel: netfilter: nf_conntrack_helper: pass helper to expect cleanup (CVE-2026-43027)

    * kernel: io_uring/rsrc: reject zero-length fixed buffer import (CVE-2026-43006)

    * kernel: Bluetooth: MGMT: validate LTK enc_size on load (CVE-2026-43020)

    * kernel: HID: wacom: fix out-of-bounds read in wacom_intuos_bt_irq (CVE-2026-43051)

    * kernel: Bluetooth: SCO: fix race conditions in sco_sock_connect() (CVE-2026-43023)

    * kernel: netfilter: ctnetlink: ensure safe access to master conntrack (CVE-2026-43116)

    * kernel: wifi: brcmfmac: validate bsscfg indices in IF events (CVE-2026-43110)

    * kernel: netfilter: xt_tcpmss: check remaining length before reading optlen (CVE-2026-43190)

    * kernel: Linux kernel dpaa2-switch: Kernel memory corruption via out-of-bounds write (CVE-2026-43205)

    * kernel: xfs: fix freemap adjustments when adding xattrs to leaf blocks (CVE-2026-43158)

    * kernel: mm/page_alloc: clear page->private in free_pages_prepare() (CVE-2026-43303)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

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

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1693 advisory.

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

    af_unix: Give up GC if MSG_PEEK intervened. (CVE-2026-23394)

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

    ipv6: add NULL checks for idev in SRv6 paths (CVE-2026-23442)

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

    netfilter: conntrack: add missing netlink policy validations (CVE-2026-31407)

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

    netfilter: ipset: drop logically empty buckets in mtype_del (CVE-2026-31418)

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

    net: skb: fix cross-cache free of KFENCE-allocated skb head (CVE-2026-31429)

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

    X.509: Fix out-of-bounds access when parsing extensions (CVE-2026-31430)

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

    ipv4: nexthop: allocate skb dynamically in rtm_get_nexthop() (CVE-2026-31531)

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

    can: raw: fix ro->uniq use-after-free in raw_rcv() (CVE-2026-31532)

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

    net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption (CVE-2026-31533)

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

    mm/userfaultfd: fix hugetlb fault mutex hash calculation (CVE-2026-31575)

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

    wireguard: device: use exit_rtnl callback instead of manual rtnl_lock in pre_exit (CVE-2026-31579)

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

    bcache: fix cached_dev.sb_bio use-after-free and crash (CVE-2026-31580)

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

    mm: blk-cgroup: fix use-after-free in cgwb_release_workfn() (CVE-2026-31586)

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

    KVM: x86: Use scratch field in MMIO fragment to hold small write values (CVE-2026-31588)

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

    KVM: SEV: Lock all vCPUs when synchronzing VMSAs for SNP launch finish (CVE-2026-31591)

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

    KVM: SEV: Protect *all* of sev_mem_enc_register_region() with kvm->lock (CVE-2026-31592)

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

    KVM: SEV: Reject attempts to sync VMSA of an already-launched/encrypted vCPU (CVE-2026-31593)

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

    arm64: mm: Handle invalid large leaf mappings correctly (CVE-2026-31600)

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

    usbip: validate number_of_packets in usbip_pack_ret_submit() (CVE-2026-31607)

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

    smb: client: fix OOB reads parsing symlink error response (CVE-2026-31613)

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

    smb: client: fix off-by-8 bounds check in check_wsl_eas() (CVE-2026-31614)

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

    HID: core: clamp report_size in s32ton() to avoid undefined shift (CVE-2026-31624)

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

    HID: alps: fix NULL pointer dereference in alps_raw_event() (CVE-2026-31625)

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

    x86/CPU: Fix FPDSS on Zen1 (CVE-2026-31628)

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

    rxrpc: fix reference count leak in rxrpc_server_keyring() (CVE-2026-31634)

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

    rxrpc: reject undecryptable rxkad response tickets (CVE-2026-31637)

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

    mm: filemap: fix nr_pages calculation overflow in filemap_map_pages() (CVE-2026-31648)

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

    mm/damon/sysfs: dealloc repeat_call_control if damon_call() fails (CVE-2026-31653)

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

    drm/i915/gt: fix refcount underflow in intel_engine_park_heartbeat (CVE-2026-31656)

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

    tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG (CVE-2026-31662)

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

    xfrm: hold dev ref until after transport_finish NF_HOOK (CVE-2026-31663)

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

    xfrm: clear trailing padding in build_polexpire() (CVE-2026-31664)

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

    netfilter: nft_ct: fix use-after-free in timeout object destroy (CVE-2026-31665)

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

    btrfs: fix incorrect return value after changing leaf in lookup_extent_data_ref() (CVE-2026-31666)

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

    Input: uinput - fix circular locking dependency with ff-core (CVE-2026-31667)

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

    seg6: separate dst_cache for input and output paths in seg6 lwtunnel (CVE-2026-31668)

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

    mptcp: fix slab-use-after-free in __inet_lookup_established (CVE-2026-31669)

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

    xfrm_user: fix info leak in build_report() (CVE-2026-31671)

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

    af_unix: read UNIX_DIAG_VFS data under unix_state_lock (CVE-2026-31673)

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

    netfilter: xt_multiport: validate range encoding in checkentry (CVE-2026-31681)

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

    net: sched: act_csum: validate nested VLAN headers (CVE-2026-31684)

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

    netfilter: ip6t_eui64: reject invalid MAC header for all packets (CVE-2026-31685)

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

    EDAC/mc: Fix error path ordering in edac_mc_alloc() (CVE-2026-31689)

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

    igb: remove napi_synchronize() in igb_down() (CVE-2026-31691)

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

    rtnetlink: add missing netlink_ns_capable() check for peer netns (CVE-2026-31692)

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

    fuse: reject oversized dirents in page cache (CVE-2026-31694)

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

    net/packet: fix TOCTOU race on mmap'd vnet_hdr in tpacket_snd() (CVE-2026-31700)

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

    writeback: Fix use after free in inode_switch_wbs_work_fn() (CVE-2026-31703)

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

    smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path (CVE-2026-31708)

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

    fuse: abort on fatal signal during sync init (CVE-2026-31713)

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

    fs/ntfs3: validate rec->used in journal-replay file record check (CVE-2026-31716)

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

    crypto: krb5enc - fix async decrypt skipping hash verification (CVE-2026-31719)

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

    dcache: Limit the minimal number of bucket to two (CVE-2026-43071)

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

    x86-64: rename misleadingly named '__copy_user_nocache()' function (CVE-2026-43073)

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

    eventpoll: defer struct eventpoll free to RCU grace period (CVE-2026-43074)

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

    perf/x86/intel/uncore: Skip discovery table for offline dies (CVE-2026-43079)

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

    net: ioam6: fix OOB and missing lock (CVE-2026-43083)

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

    netfilter: nfnetlink_queue: make hash table per queue (CVE-2026-43084)

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

    netfilter: nfnetlink_log: initialize nfgenmsg in NLMSG_DONE terminator (CVE-2026-43085)

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

    ipvs: fix NULL deref in ip_vs_add_service error path (CVE-2026-43086)

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

    xfrm_user: fix info leak in build_mapping() (CVE-2026-43089)

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

    xfrm: fix refcount leak in xfrm_migrate_policy_find (CVE-2026-43090)

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

    xfrm: Wait for RCU readers during policy netns exit (CVE-2026-43091)

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

    xsk: validate MTU against usable frame size on bind (CVE-2026-43092)

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

    xsk: tighten UMEM headroom validation to account for tailroom and min frame (CVE-2026-43093)

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

    ixgbevf: add missing negotiate_features op to Hyper-V ops table (CVE-2026-43094)

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

    ipv4: icmp: fix null-ptr-deref in icmp_build_probe() (CVE-2026-43099)

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

    bridge: guard local VLAN-0 FDB helpers against NULL vlan group (CVE-2026-43100)

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

    ipv6: ioam: fix potential NULL dereferences in __ioam6_fill_trace_data() (CVE-2026-43101)

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

    xfrm: account XFRMA_IF_ID in aevent size calculation (CVE-2026-43107)

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

    x86: shadow stacks: proper error handling for mmap lock (CVE-2026-43109)

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

    fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath (CVE-2026-43112)

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

    netfilter: nft_set_pipapo_avx2: don't return non-matching entry on expiry (CVE-2026-43114)

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

    netfilter: ctnetlink: ensure safe access to master conntrack (CVE-2026-43116)

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

    btrfs: tracepoints: get correct superblock from dentry in event btrfs_sync_file() (CVE-2026-43117)

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

    btrfs: fix zero size inode with non-zero size after log replay (CVE-2026-43118)

    In the Linux kernel, the following vulnerability has been resolved:xfrm: esp: avoid in-place decrypt on     shared skb frags

    Dirty Frag and other issues in Amazon Linux kernels:https://aws.amazon.com/security/security-     bulletins/2026-027-aws/ (CVE-2026-43284)

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

    smb: client: require a full NFS mode SID before reading mode bits (CVE-2026-43350)

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

  - netfilter: ctnetlink: ensure safe access to master conntrack Holding reference on the expectation is not     sufficient, the master conntrack object can just go away, making exp->master invalid. To access     exp->master safely: - Grab the nf_conntrack_expect_lock, this gets serialized with clean_from_lists()     which also holds this lock when the master conntrack goes away. - Hold reference on master conntrack via     nf_conntrack_find_get(). Not so easy since the master tuple to look up for the master conntrack is not     available in the existing problematic paths. This patch goes for extending the nf_conntrack_expect_lock     section to address this issue for simplicity, in the cases that are described below this is just slightly     extending the lock section. The add expectation command already holds a reference to the master conntrack     from ctnetlink_create_expect(). However, the delete expectation command needs to grab the spinlock before     looking up for the expectation. Expand the existing spinlock section to address this to cover the     expectation lookup. Note that, the nf_ct_expect_iterate_net() calls already grabs the spinlock while     iterating over the expectation table, which is correct. The get expectation command needs to grab the     spinlock to ensure master conntrack does not go away. This also expands the existing spinlock section to     cover the expectation lookup too. I needed to move the netlink skb allocation out of the spinlock to keep     it GFP_KERNEL. For the expectation events, the IPEXP_DESTROY event is already delivered under the     spinlock, just move the delivery of IPEXP_NEW under the spinlock too because the master conntrack event     cache is reached through exp->master. While at it, add lockdep notations to help identify what codepaths     need to grab the spinlock. (CVE-2026-43116)

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

ID	Name	Product	Family	Severity
317380	RHEL 10 : kernel (RHSA-2026:21557)	Nessus	Red Hat Local Security Checks	high
313525	Amazon Linux 2023 : bpftool6.18, kernel6.18, kernel6.18-devel (ALAS2023-2026-1693)	Nessus	Amazon Linux Local Security Checks	high
312643	Linux Distros Unpatched Vulnerability : CVE-2026-43116	Nessus	Misc.	high

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