{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-23248",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-01-13T15:37:45.989Z",
        "datePublished": "2026-03-18T10:05:10.070Z",
        "dateUpdated": "2026-08-05T12:20:56.308Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-08-05T12:20:56.308Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "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."
                }
            ],
            "metrics": [
                {
                    "cvssV3_1": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                        "baseScore": 7.8,
                        "baseSeverity": "HIGH"
                    },
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "AV:L - The vulnerability is triggered via the perf_event_open() syscall followed by mmap() on the resulting file descriptor, requiring local system access.\nAC:L - The attacker controls both sides of the race by spawning two threads that concurrently mmap() the same perf event fd. Per CVSS guidance, attacker-controlled races are AC:L.\nPR:L - Unprivileged local users can use perf_event_open() with exclude_kernel=1 and per-task events (cpu=-1) even with the default perf_event_paranoid=2, then mmap() the resulting fd to trigger the race.\nUI:N - No user interaction is needed; the attacker creates the perf event and triggers the race entirely on their own.\nS:U - This is a standard kernel use-after-free for privilege escalation within the same security authority; no VM escape or sandbox boundary crossing occurs.\nC:H - The UAF on the perf_buffer heap object allows the attacker to spray controlled data into the freed slab, enabling arbitrary kernel memory reads through the buffer's data page pointers and user_page.\nI:H - The freed perf_buffer contains function pointers (free_aux) and is accessed through multiple code paths, enabling heap spraying for arbitrary write primitives and control flow hijacking.\nA:H - The use-after-free reliably causes kernel crashes (refcount saturation warnings, oops, or panic) when the freed ring buffer is accessed."
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "kernel/events/core.c"
                    ],
                    "versions": [
                        {
                            "version": "b709eb872e19a19607bbb6d2975bc264d59735cf",
                            "lessThan": "c27dea9f50ed525facb62ef647dddc4722456e07",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "b709eb872e19a19607bbb6d2975bc264d59735cf",
                            "lessThan": "ac7ecb65af170a7fc193e7bd8be15dac84ec6a56",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "b709eb872e19a19607bbb6d2975bc264d59735cf",
                            "lessThan": "77de62ad3de3967818c3dbe656b7336ebee461d2",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "kernel/events/core.c"
                    ],
                    "versions": [
                        {
                            "version": "6.14",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.14",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.17",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.19.7",
                            "lessThanOrEqual": "6.19.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.0",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "operator": "OR",
                            "negate": false,
                            "cpeMatch": [
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.14",
                                    "versionEndExcluding": "6.18.17"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.14",
                                    "versionEndExcluding": "6.19.7"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.14",
                                    "versionEndExcluding": "7.0"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/c27dea9f50ed525facb62ef647dddc4722456e07"
                },
                {
                    "url": "https://git.kernel.org/stable/c/ac7ecb65af170a7fc193e7bd8be15dac84ec6a56"
                },
                {
                    "url": "https://git.kernel.org/stable/c/77de62ad3de3967818c3dbe656b7336ebee461d2"
                }
            ],
            "title": "perf/core: Fix refcount bug and potential UAF in perf_mmap",
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    }
}