CVE-2026-23248 (GCVE-0-2026-23248)
Vulnerability from cvelistv5
Published
2026-03-18 10:05
Modified
2026-10-19 18:35
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix refcount bug and potential UAF in perf_mmap Syzkaller reported a refcount_t: addition on 0; use-after-free warning in perf_mmap. The issue is caused by a race condition between a failing mmap() setup and a concurrent mmap() on a dependent event (e.g., using output redirection). In perf_mmap(), the ring_buffer (rb) is allocated and assigned to event->rb with the mmap_mutex held. The mutex is then released to perform map_range(). If map_range() fails, perf_mmap_close() is called to clean up. However, since the mutex was dropped, another thread attaching to this event (via inherited events or output redirection) can acquire the mutex, observe the valid event->rb pointer, and attempt to increment its reference count. If the cleanup path has already dropped the reference count to zero, this results in a use-after-free or refcount saturation warning. Fix this by extending the scope of mmap_mutex to cover the map_range() call. This ensures that the ring buffer initialization and mapping (or cleanup on failure) happens atomically effectively, preventing other threads from accessing a half-initialized or dying ring buffer.
References
Impacted products
Vendor Product Version
Linux Linux Version: b709eb872e19a19607bbb6d2975bc264d59735cf
Version: b709eb872e19a19607bbb6d2975bc264d59735cf
Version: b709eb872e19a19607bbb6d2975bc264d59735cf
 Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-23248",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-16T15:06:58.307161Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-362",
                "description": "CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027)",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-19T18:35:40.258Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/events/core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "c27dea9f50ed525facb62ef647dddc4722456e07",
              "status": "affected",
              "version": "b709eb872e19a19607bbb6d2975bc264d59735cf",
              "versionType": "git"
            },
            {
              "lessThan": "ac7ecb65af170a7fc193e7bd8be15dac84ec6a56",
              "status": "affected",
              "version": "b709eb872e19a19607bbb6d2975bc264d59735cf",
              "versionType": "git"
            },
            {
              "lessThan": "77de62ad3de3967818c3dbe656b7336ebee461d2",
              "status": "affected",
              "version": "b709eb872e19a19607bbb6d2975bc264d59735cf",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/events/core.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
            },
            {
              "lessThan": "6.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.17",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.17",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.7",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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-\u003erb 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-\u003erb 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"
          },
          "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\u0027s 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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:20:56.308Z",
        "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": "2026-10-19T18:35:40.258Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-23248\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-10-16T15:06:58.307161Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-362\", \"description\": \"CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027)\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-10-16T15:06:58.836Z\"}}], \"cna\": {\"title\": \"perf/core: Fix refcount bug and potential UAF in perf_mmap\", \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"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\"}, \"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\u0027s 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\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"b709eb872e19a19607bbb6d2975bc264d59735cf\", \"lessThan\": \"c27dea9f50ed525facb62ef647dddc4722456e07\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"b709eb872e19a19607bbb6d2975bc264d59735cf\", \"lessThan\": \"ac7ecb65af170a7fc193e7bd8be15dac84ec6a56\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"b709eb872e19a19607bbb6d2975bc264d59735cf\", \"lessThan\": \"77de62ad3de3967818c3dbe656b7336ebee461d2\", \"versionType\": \"git\"}], \"programFiles\": [\"kernel/events/core.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"6.14\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"6.14\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"6.18.17\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.18.*\"}, {\"status\": \"unaffected\", \"version\": \"6.19.7\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.19.*\"}, {\"status\": \"unaffected\", \"version\": \"7.0\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"kernel/events/core.c\"], \"defaultStatus\": \"affected\"}], \"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\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"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-\u003erb 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-\u003erb 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.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.18.17\", \"versionStartIncluding\": \"6.14\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.19.7\", \"versionStartIncluding\": \"6.14\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.0\", \"versionStartIncluding\": \"6.14\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T12:20:56.308Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-23248\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-19T18:35:40.258Z\", \"dateReserved\": \"2026-01-13T15:37:45.989Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-03-18T10:05:10.070Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.