{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2025-40123", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-40123", "idYear": 2025, "status": "PUBLISHED", "publishedAt": "2025-11-12T10:23:19.589Z", "updatedAt": "2026-10-15T22:02:38.256Z", "importedAt": "2026-10-24T01:57:34.152Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "bpf: Enforce expected_attach_type for tailcall compatibility", "summary": "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.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "5e43f899b03a3492ce5fc44e8900becb04dae9c0", "status": "affected", "versionType": "git", "lessThan": "e53a59e7cee5c1605d1ed595933098c2b69108f9" }, { "version": "5e43f899b03a3492ce5fc44e8900becb04dae9c0", "status": "affected", "versionType": "git", "lessThan": "dc4f348952173beb8ceb15be30b249276eccb605" }, { "version": "5e43f899b03a3492ce5fc44e8900becb04dae9c0", "status": "affected", "versionType": "git", "lessThan": "a99de19128aec0913f3d529f529fbbff5edfaff8" }, { "version": "5e43f899b03a3492ce5fc44e8900becb04dae9c0", "status": "affected", "versionType": "git", "lessThan": "08cb3dc9d2b44f153d0bcf2cb966e4a94b5d0f32" }, { "version": "5e43f899b03a3492ce5fc44e8900becb04dae9c0", "status": "affected", "versionType": "git", "lessThan": "f856c598080ba7ce1252867b8ecd6ad5bdaf9a6a" }, { "version": "5e43f899b03a3492ce5fc44e8900becb04dae9c0", "status": "affected", "versionType": "git", "lessThan": "c1ad19b5d8e23123503dcaf2d4342e1b90b923ad" }, { "version": "5e43f899b03a3492ce5fc44e8900becb04dae9c0", "status": "affected", "versionType": "git", "lessThan": "4540aed51b12bc13364149bf95f6ecef013197c0" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "4.17", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "4.17" }, { "version": "5.10.270", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.221", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.156", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.112", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.53", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.17.3", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.17.*" }, { "version": "6.18", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }