Vulnerability-Lookup

CVE-2026-23248 (GCVE-0-2026-23248)

Vulnerability from cvelistv5 – Published: 2026-03-18 10:05 – Updated: 2026-03-18 16:21

Title

perf/core: Fix refcount bug and potential UAF in perf_mmap

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.

Severity ?

No CVSS data available.

Assigner

Linux

References

URL

Tags

	https://git.kernel.org/stable/c/c27dea9f50ed525fa…
	https://git.kernel.org/stable/c/ac7ecb65af170a7fc…
	https://git.kernel.org/stable/c/77de62ad3de396781…

Impacted products

Vendor

Product

Version

Linux

Affected: b709eb872e19a19607bbb6d2975bc264d59735cf , < c27dea9f50ed525facb62ef647dddc4722456e07 (git)
Affected: b709eb872e19a19607bbb6d2975bc264d59735cf , < ac7ecb65af170a7fc193e7bd8be15dac84ec6a56 (git)
Affected: b709eb872e19a19607bbb6d2975bc264d59735cf , < 77de62ad3de3967818c3dbe656b7336ebee461d2 (git)

Linux

Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.18.17 , ≤ 6.18.* (semver)
Unaffected: 6.19.7 , ≤ 6.19.* (semver)
Unaffected: 7.0-rc2 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/events/core.c"
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          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "b709eb872e19a19607bbb6d2975bc264d59735cf",
              "versionType": "git"
            },
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              "status": "affected",
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              "versionType": "git"
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              "status": "affected",
              "version": "b709eb872e19a19607bbb6d2975bc264d59735cf",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "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-rc2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
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                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.7",
                  "versionStartIncluding": "6.14",
                  "vulnerable": true
                },
                {
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                  "versionEndExcluding": "7.0-rc2",
                  "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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-18T16:21:48.553Z",
        "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",
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        "engine": "bippy-1.2.0"
      }
    }
  },
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23248",
    "datePublished": "2026-03-18T10:05:10.070Z",
    "dateReserved": "2026-01-13T15:37:45.989Z",
    "dateUpdated": "2026-03-18T16:21:48.553Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23248\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-03-18T11:16:16.863\",\"lastModified\":\"2026-03-18T14:52:44.227\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"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\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/77de62ad3de3967818c3dbe656b7336ebee461d2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ac7ecb65af170a7fc193e7bd8be15dac84ec6a56\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/c27dea9f50ed525facb62ef647dddc4722456e07\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}

GHSA-78FW-H7FP-FFFH

Vulnerability from github – Published: 2026-03-18 12:31 – Updated: 2026-03-18 12:31

Details

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.

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-23248"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-03-18T11:16:16Z",
    "severity": null
  },
  "details": "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.",
  "id": "GHSA-78fw-h7fp-fffh",
  "modified": "2026-03-18T12:31:52Z",
  "published": "2026-03-18T12:31:52Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23248"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/77de62ad3de3967818c3dbe656b7336ebee461d2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ac7ecb65af170a7fc193e7bd8be15dac84ec6a56"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c27dea9f50ed525facb62ef647dddc4722456e07"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

FKIE_CVE-2026-23248

Vulnerability from fkie_nvd - Published: 2026-03-18 11:16 - Updated: 2026-03-18 14:52

Severity ?

Summary

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/77de62ad3de3967818c3dbe656b7336ebee461d2
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/ac7ecb65af170a7fc193e7bd8be15dac84ec6a56
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/c27dea9f50ed525facb62ef647dddc4722456e07

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "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."
    }
  ],
  "id": "CVE-2026-23248",
  "lastModified": "2026-03-18T14:52:44.227",
  "metrics": {},
  "published": "2026-03-18T11:16:16.863",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/77de62ad3de3967818c3dbe656b7336ebee461d2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ac7ecb65af170a7fc193e7bd8be15dac84ec6a56"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c27dea9f50ed525facb62ef647dddc4722456e07"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-23248 (GCVE-0-2026-23248)

GHSA-78FW-H7FP-FFFH

FKIE_CVE-2026-23248

Tags

Sightings

Nomenclature