{"id":"CVE-2026-23248","revision":"c067b6d258b448a28a83bd3af21def7d","records":[{"revision":"c067b6d258b448a28a83bd3af21def7d","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-23248","aliases":[],"title":"perf/core: Fix refcount bug and potential UAF in perf_mmap","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/core: Fix refcount bug and potential UAF in perf_mmap\n\nSyzkaller reported a refcount_t: addition on 0; use-after-free warning\nin perf_mmap.\n\nThe issue is caused by a race condition between a failing mmap() setup\nand a concurrent mmap() on a dependent event (e.g., using output\nredirection).\n\nIn perf_mmap(), the ring_buffer (rb) is allocated and assigned to\nevent->rb with the mmap_mutex held. The mutex is then released to\nperform map_range().\n\nIf map_range() fails, perf_mmap_close() is called to clean up.\nHowever, since the mutex was dropped, another thread attaching to\nthis event (via inherited events or output redirection) can acquire\nthe mutex, observe the valid event->rb pointer, and attempt to\nincrement its reference count. If the cleanup path has already\ndropped the reference count to zero, this results in a\nuse-after-free or refcount saturation warning.\n\nFix this by extending the scope of mmap_mutex to cover the\nmap_range() call. This ensures that the ring buffer initialization\nand mapping (or cleanup on failure) happens atomically effectively,\npreventing other threads from accessing a half-initialized or\ndying ring buffer.","state":0,"publishedAt":"2026-03-18T10:05:10.07+00:00","modifiedAt":"2026-10-19T18:35:40.258+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/events/core.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"b709eb872e19a19607bbb6d2975bc264d59735cf\",\n                            \"lessThan\": \"c27dea9f50ed525facb62ef647dddc4722456e07\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b709eb872e19a19607bbb6d2975bc264d59735cf\",\n                            \"lessThan\": \"ac7ecb65af170a7fc193e7bd8be15dac84ec6a56\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b709eb872e19a19607bbb6d2975bc264d59735cf\",\n                            \"lessThan\": \"77de62ad3de3967818c3dbe656b7336ebee461d2\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"kernel/events/core.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.14\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.14\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.17\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.19.7\",\n                            \"lessThanOrEqual\": \"6.19.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/c27dea9f50ed525facb62ef647dddc4722456e07","https://git.kernel.org/stable/c/ac7ecb65af170a7fc193e7bd8be15dac84ec6a56","https://git.kernel.org/stable/c/77de62ad3de3967818c3dbe656b7336ebee461d2"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-23248","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-23248","identifiers":["CVE-2026-23248"]},"retained":false,"historicalAffected":[]}],"coverage":[]}