{"cve":"CVE-2025-38591","nvd":{"published":"2025-08-19T17:15:36.790","modified":"2026-10-15T02:17:56.007","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject narrower access to pointer ctx fields\n\nThe following BPF program, simplified from a syzkaller repro, causes a\nkernel warning:\n\n    r0 = *(u8 *)(r1 + 169);\n    exit;\n\nWith pointer field sk being at offset 168 in __sk_buff. This access is\ndetected as a narrower read in bpf_skb_is_valid_access because it\ndoesn't match offsetof(struct __sk_buff, sk). It is therefore allowed\nand later proceeds to bpf_convert_ctx_access. Note that for the\n\"is_narrower_load\" case in the convert_ctx_accesses(), the insn->off\nis aligned, so the cnt may not be 0 because it matches the\noffsetof(struct __sk_buff, sk) in the bpf_convert_ctx_access. However,\nthe target_size stays 0 and the verifier errors with a kernel warning:\n\n    verifier bug: error during ctx access conversion(1)\n\nThis patch fixes that to return a proper \"invalid bpf_context access\noff=X size=Y\" error on the load instruction.\n\nThe same issue affects multiple other fields in context structures that\nallow narrow access. Some other non-affected fields (for sk_msg,\nsk_lookup, and sockopt) were also changed to use bpf_ctx_range_ptr for\nconsistency.\n\nNote this syzkaller crash was reported in the \"Closes\" link below, which\nused to be about a different bug, fixed in\ncommit fce7bd8e385a (\"bpf/verifier: Handle BPF_LOAD_ACQ instructions\nin insn_def_regno()\"). Because syzbot somehow confused the two bugs,\nthe new crash and repro didn't get reported to the mailing list.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/058a0da4f6d916a79b693384111bb80a90d73763","https://git.kernel.org/stable/c/202900ceeef67458c964c2af6e1427c8e533ea7c","https://git.kernel.org/stable/c/33660d44e789edb4f303210c813fc56d56377a90","https://git.kernel.org/stable/c/7847c4140e06f6e87229faae22cc38525334c156","https://git.kernel.org/stable/c/e09299225d5ba3916c91ef70565f7d2187e4cca0"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:07:46.309729541+00:00"},"epss":{"cve":"CVE-2025-38591","score":0.0021,"percentile":0.11131,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}