{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2025-40123 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-40123 is a high-severity vulnerability in Linux, published on 12 Nov 2025. 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-2025-40123 and fix it if it is affected.\n\nWhat it is: CVE-2025-40123 is a high-severity vulnerability in Linux, published on 12 Nov 2025. 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-2025-40123 in the wild and no public exploit code.\n\nAffected product: Linux. 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-2025-40123/ (Markdown: https://insights.sbomify.com/CVE-2025-40123/index.md)","id":"CVE-2025-40123","markdown":"https://insights.sbomify.com/CVE-2025-40123/index.md","name":"CVE-2025-40123","record":{"aliases":["BELL-CVE-2025-40123","DEBIAN-CVE-2025-40123","GHSA-f5hr-qj5q-hc8f","ROOT-OS-DEBIAN-11-CVE-2025-40123","ROOT-OS-UBUNTU-2204-CVE-2025-40123","ROOT-OS-UBUNTU-2404-CVE-2025-40123","UBUNTU-CVE-2025-40123"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel BPF","requires_auth":"low_privilege","summary":"A missing check in the Linux kernel BPF subsystem allows a NULL pointer dereference via tailcalls, leading to a denial of service.","user_interaction":"not_required","vuln_class":"null_dereference"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[],"cvss":{"score":7.8,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Enforce expected_attach_type for tailcall compatibility\n\nYinhao et al. recently reported:\n\n  Our fuzzer tool discovered an uninitialized pointer issue in the\n  bpf_prog_test_run_xdp() function within the Linux kernel's BPF subsystem.\n  This leads to a NULL pointer dereference when a BPF program attempts to\n  deference the txq member of struct xdp_buff object.\n\nThe test initializes two programs of BPF_PROG_TYPE_XDP: progA acts as the\nentry point for bpf_prog_test_run_xdp() and its expected_attach_type can\nneither be of be BPF_XDP_DEVMAP nor BPF_XDP_CPUMAP. progA calls into a slot\nof a tailcall map it owns. progB's expected_attach_type must be BPF_XDP_DEVMAP\nto pass xdp_is_valid_access() validation. The program returns struct xdp_md's\negress_ifindex, and the latter is only allowed to be accessed under mentioned\nexpected_attach_type. progB is then inserted into the tailcall which progA\ncalls.\n\nThe underlying issue goes beyond XDP though. Another example are programs\nof type BPF_PROG_TYPE_CGROUP_SOCK_ADDR. sock_addr_is_valid_access() as well\nas sock_addr_func_proto() have different logic depending on the programs'\nexpected_attach_type. Similarly, a program attached to BPF_CGROUP_INET4_GETPEERNAME\nshould not be allowed doing a tailcall into a program which calls bpf_bind()\nout of BPF which is only enabled for BPF_CGROUP_INET4_CONNECT.\n\nIn short, specifying expected_attach_type allows to open up additional\nfunctionality or restrictions beyond what the basic bpf_prog_type enables.\nThe use of tailcalls must not violate these constraints. Fix it by enforcing\nexpected_attach_type in __bpf_prog_map_compatible().\n\nNote that we only enforce this for tailcall maps, but not for BPF devmaps or\ncpumaps: There, the programs are invoked through dev_map_bpf_prog_run*() and\ncpu_map_bpf_prog_run*() which set up a new environment / context and therefore\nthese situations are not prone to this issue.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":"2026-08-24","github_poc":1,"max_poc_stars":0,"metasploit":0,"nuclei":0,"refs":[{"date":"2026-08-24T03:03:45Z","kind":"github_poc","ref":"https://github.com/gduma-phData/patch-CVE-2025-40123","stars":0,"title":"Patch: Deserialization RCE (Veeam Backup)"}],"tier":"poc_unverified"},"has_fix":true,"headline":"bpf: Enforce expected_attach_type for tailcall compatibility","id":"CVE-2025-40123","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"null_dereference","year":"2025"},"n_packages":0,"n_references":7,"next":{"headline":"sparc: fix accurate exception reporting in copy_{from_to}_user for UltraSPARC III","id":"CVE-2025-40124"},"packages":[],"prev":{"headline":"perf/x86/intel: Fix IA32_PMC_x_CFG_B MSRs access error","id":"CVE-2025-40122"},"products":["Linux"],"published":"2025-11-12","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"},{"class":"open","licence":"CC0","name":"PoC-in-GitHub"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-10-15","vendors":["Linux"]},"summary":"A missing check in the Linux kernel BPF subsystem allows a NULL pointer dereference via tailcalls, leading to a denial of service.","url":"https://insights.sbomify.com/CVE-2025-40123/"}