{"api_version":"1","generated_at":"2026-04-08T01:27:58+00:00","cve":"CVE-2026-23248","urls":{"html":"https://cve.report/CVE-2026-23248","api":"https://cve.report/api/cve/CVE-2026-23248.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-23248","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-23248"},"summary":{"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":"PUBLISHED","assigner":"Linux","published_at":"2026-03-18 11:16:16","updated_at":"2026-04-02 15:16:27"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/ac7ecb65af170a7fc193e7bd8be15dac84ec6a56","name":"https://git.kernel.org/stable/c/ac7ecb65af170a7fc193e7bd8be15dac84ec6a56","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/77de62ad3de3967818c3dbe656b7336ebee461d2","name":"https://git.kernel.org/stable/c/77de62ad3de3967818c3dbe656b7336ebee461d2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c27dea9f50ed525facb62ef647dddc4722456e07","name":"https://git.kernel.org/stable/c/c27dea9f50ed525facb62ef647dddc4722456e07","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-23248","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-23248","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b709eb872e19a19607bbb6d2975bc264d59735cf c27dea9f50ed525facb62ef647dddc4722456e07 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b709eb872e19a19607bbb6d2975bc264d59735cf ac7ecb65af170a7fc193e7bd8be15dac84ec6a56 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b709eb872e19a19607bbb6d2975bc264d59735cf 77de62ad3de3967818c3dbe656b7336ebee461d2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.14","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.14 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.17 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.7 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0-rc2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"23248","cve":"CVE-2026-23248","epss":"0.000130000","percentile":"0.021630000","score_date":"2026-04-07","updated_at":"2026-04-08 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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":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-04-02T14:43:59.911Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-23248","datePublished":"2026-03-18T10:05:10.070Z","dateReserved":"2026-01-13T15:37:45.989Z","dateUpdated":"2026-04-02T14:43:59.911Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-03-18 11:16:16","lastModifiedDate":"2026-04-02 15:16:27","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"23248","Ordinal":"1","Title":"perf/core: Fix refcount bug and potential UAF in perf_mmap","CVE":"CVE-2026-23248","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"23248","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"perf/core: Fix refcount bug and potential UAF in perf_mmap"}]}}}