{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-23342 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-23342 is a medium-severity vulnerability in Linux kernel, published on 25 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-23342 and fix it if it is affected.\n\nWhat it is: CVE-2026-23342 is a medium-severity vulnerability in Linux kernel, published on 25 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-23342 in the wild and no public exploit code.\n\nAffected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-23342/ (Markdown: https://insights.sbomify.com/CVE-2026-23342/index.md)","id":"CVE-2026-23342","markdown":"https://insights.sbomify.com/CVE-2026-23342/index.md","name":"CVE-2026-23342","record":{"aliases":["BELL-CVE-2026-23342","DEBIAN-CVE-2026-23342","GHSA-c898-7qpg-fw83","UBUNTU-CVE-2026-23342"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service","code_execution"],"network_reachable":"adjacent_or_local","non_default_config":true,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"A race condition in the Linux kernel's BPF cpumap on PREEMPT_RT systems allows concurrent access to per-CPU queues, potentially leading to memory corruption or crashes.","user_interaction":"not_required","vuln_class":"race_condition"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":4.7,"severity":"medium","source":"nvd","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-362","name":"Concurrent Execution using Shared Resource with Improper Synchronization"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix race in cpumap on PREEMPT_RT\n\nOn PREEMPT_RT kernels, the per-CPU xdp_bulk_queue (bq) can be accessed\nconcurrently by multiple preemptible tasks on the same CPU.\n\nThe original code assumes bq_enqueue() and __cpu_map_flush() run\natomically with respect to each other on the same CPU, relying on\nlocal_bh_disable() to prevent preemption. However, on PREEMPT_RT,\nlocal_bh_disable() only calls migrate_disable() (when\nPREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable\npreemption, which allows CFS scheduling to preempt a task during\nbq_flush_to_queue(), enabling another task on the same CPU to enter\nbq_enqueue() and operate on the same per-CPU bq concurrently.\n\nThis leads to several races:\n\n1. Double __list_del_clearprev(): after bq-\u003ecount is reset in\n   bq_flush_to_queue(), a preempting task can call bq_enqueue() -\u003e\n   bq_flush_to_queue() on the same bq when bq-\u003ecount reaches\n   CPU_MAP_BULK_SIZE. Both tasks then call __list_del_clearprev()\n   on the same bq-\u003eflush_node, the second call dereferences the\n   prev pointer that was already set to NULL by the first.\n\n2. bq-\u003ecount and bq-\u003eq[] races: concurrent bq_enqueue() can corrupt\n   the packet queue while bq_flush_to_queue() is processing it.\n\nThe race between task A (__cpu_map_flush -\u003e bq_flush_to_queue) and\ntask B (bq_enqueue -\u003e bq_flush_to_queue) on the same CPU:\n\n  Task A (xdp_do_flush)          Task B (cpu_map_enqueue)\n  ----------------------         ------------------------\n  bq_flush_to_queue(bq)\n    spin_lock(\u0026q-\u003eproducer_lock)\n    /* flush bq-\u003eq[] to ptr_ring */\n    bq-\u003ecount = 0\n    spin_unlock(\u0026q-\u003eproducer_lock)\n                                   bq_enqueue(rcpu, xdpf)\n    \u003c-- CFS preempts Task A --\u003e      bq-\u003eq[bq-\u003ecount++] = xdpf\n                                     /* ... more enqueues until full ... */\n                                     bq_flush_to_queue(bq)\n                                       spin_lock(\u0026q-\u003eproducer_lock)\n                                       /* flush to ptr_ring */\n                                       spin_unlock(\u0026q-\u003eproducer_lock)\n                                       __list_del_clearprev(flush_node)\n                                         /* sets flush_node.prev = NULL */\n    \u003c-- Task A resumes --\u003e\n    __list_del_clearprev(flush_node)\n      flush_node.prev-\u003enext = ...\n      /* prev is NULL -\u003e kernel oops */\n\nFix this by adding a local_lock_t to xdp_bulk_queue and acquiring it\nin bq_enqueue() and __cpu_map_flush(). These paths already run under\nlocal_bh_disable(), so use local_lock_nested_bh() which on non-RT is\na pure annotation with no overhead, and on PREEMPT_RT provides a\nper-CPU sleeping lock that serializes access to the bq.\n\nTo reproduce, insert an mdelay(100) between bq-\u003ecount = 0 and\n__list_del_clearprev() in bq_flush_to_queue(), then run reproducer\nprovided by syzkaller.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"bpf: Fix race in cpumap on PREEMPT_RT","id":"CVE-2026-23342","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"race_condition","year":"2026"},"n_packages":0,"n_references":3,"next":{"headline":"xdp: produce a warning when calculated tailroom is negative","id":"CVE-2026-23343"},"packages":[],"prev":{"headline":"accel/amdxdna: Fix crash when destroying a suspended hardware context","id":"CVE-2026-23341"},"products":["Linux"],"published":"2026-03-25","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-05-11","vendors":["Linux"]},"summary":"A race condition in the Linux kernel's BPF cpumap on PREEMPT_RT systems allows concurrent access to per-CPU queues, potentially leading to memory corruption or crashes.","url":"https://insights.sbomify.com/CVE-2026-23342/"}