{"cve":"CVE-2026-98643","nvd":{"published":"2026-10-18T16:17:17.490","modified":"2026-10-19T10:19:28.573","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix out-of-bounds read of rtt_min in sock_ops\n\nA sockops prog reading skops->rtt_min never checks the sk type: on the\ntcp_conn_request() path sock_ops->sk is a request_sock (non-full), and the\nctx rewrite casts it to a tcp_sock (full) and reads rtt_min past the end of\nthe request_sock, returning dirty adjacent memory.\n\n\tSEC(\"sockops\")\n\tint prog(struct bpf_sock_ops *skops)\n\t{\n\t\tswitch (skops->op) {\n\t\tcase BPF_SOCK_OPS_RWND_INIT:\n\t\t\tleak = skops->rtt_min;   /* reads the request_sock OOB */\n\t\t...\n\t\t}\n\t}\n\nFor instance one such read returned rtt_min=0xffff8881, the high half of a\nleaked kernel pointer.\n\nGuarding that cast is exactly what SOCK_OPS_GET_FIELD() does -- it checks\nis_locked_tcp_sock and returns 0 when sock_ops->sk is not a locked full\nsocket. Every other tcp_sock field in sock_ops goes through it; rtt_min is\nthe only one open-coded, so it skips the check.\n\nRead rtt_min through SOCK_OPS_GET_FIELD() too. rtt_min is a bit special:\nit is a struct minmax and we only want the current min, so pass\nrtt_min.s[0].v. That is equivalent to the old hand-computed offset\n\n\toffsetof(struct tcp_sock, rtt_min) + sizeof_field(struct minmax_sample, t)\n\n(s[0] sits at rtt_min + 0 and .v at + sizeof(.t), i.e. what minmax_get()\nreturns), so the loaded field is unchanged and only the full-sock guard is\nadded. The two BUILD_BUG_ON()s that protected the hand-computed offset\nare no longer needed.\n\nBefore patch:\n\n\t0: r1 = *(u64 *)(r1 +0)      ; r1 = skops->sk\n\t1: r1 = *(u32 *)(r1 +2324)   ; ((tcp_sock *)sk)->rtt_min.s[0].v\n\nAfter patch:\n\n\t0: *(u64 *)(r1 +56) = r9\n\t1: r9 = *(u8 *)(r1 +50)      ; is_locked_tcp_sock\n\t2: if r9 == 0 goto pc+4      ; not a locked full sock -> 0\n\t3: r9 = *(u64 *)(r1 +56)\n\t4: r1 = *(u64 *)(r1 +0)      ; r1 = skops->sk\n\t5: r1 = *(u32 *)(r1 +2324)   ; rtt_min.s[0].v\n\t6: goto pc+2\n\t7: r9 = *(u64 *)(r1 +56)\n\t8: r1 = 0","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/0c796efa919f52f788c22c79d1f1b70321696b3d","https://git.kernel.org/stable/c/3a46f14e6cf375f3ca38f8f6e6524749e24ea0a8","https://git.kernel.org/stable/c/6785313d4fac96afb21ef193610c1fa88b1a9e64","https://git.kernel.org/stable/c/75f8cf22463d82bb1fb0239a3d485fc8f4c8ef03","https://git.kernel.org/stable/c/a8a9becbac93a9f54f4d565f1f3005eb08a7912f"],"products":[],"source":"nvd","synced_at":"2026-10-19T23:00:53.604569364+00:00"},"epss":{"cve":"CVE-2026-98643","score":0.00211,"percentile":0.11191,"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."]}