Vulnerability-Lookup

CVE-2026-23127 (GCVE-0-2026-23127)

Vulnerability from cvelistv5 – Published: 2026-02-14 15:09 – Updated: 2026-02-14 15:09

Title

perf: Fix refcount warning on event->mmap_count increment

Summary

In the Linux kernel, the following vulnerability has been resolved: perf: Fix refcount warning on event->mmap_count increment When calling refcount_inc(&event->mmap_count) inside perf_mmap_rb(), the following warning is triggered: refcount_t: addition on 0; use-after-free. WARNING: lib/refcount.c:25 PoC: struct perf_event_attr attr = {0}; int fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0); mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); int victim = syscall(__NR_perf_event_open, &attr, 0, -1, fd, PERF_FLAG_FD_OUTPUT); mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, victim, 0); This occurs when creating a group member event with the flag PERF_FLAG_FD_OUTPUT. The group leader should be mmap-ed and then mmap-ing the event triggers the warning. Since the event has copied the output_event in perf_event_set_output(), event->rb is set. As a result, perf_mmap_rb() calls refcount_inc(&event->mmap_count) when event->mmap_count = 0. Disallow the case when event->mmap_count = 0. This also prevents two events from updating the same user_page.

Severity ?

No CVSS data available.

Assigner

Linux

References

URL

Tags

	https://git.kernel.org/stable/c/23c0e4bd93d0b2507…
	https://git.kernel.org/stable/c/d06bf78e55d5159c1…

Impacted products

Vendor

Product

Version

Linux

Affected: 448f97fba9013ffa13f5dd82febd18836b189499 , < 23c0e4bd93d0b250775162faf456470485ac9fc7 (git)
Affected: 448f97fba9013ffa13f5dd82febd18836b189499 , < d06bf78e55d5159c1b00072e606ab924ffbbad35 (git)

Linux

Affected: 6.18
Unaffected: 0 , < 6.18 (semver)
Unaffected: 6.18.8 , ≤ 6.18.* (semver)
Unaffected: 6.19 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

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{
  "containers": {
    "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": "23c0e4bd93d0b250775162faf456470485ac9fc7",
              "status": "affected",
              "version": "448f97fba9013ffa13f5dd82febd18836b189499",
              "versionType": "git"
            },
            {
              "lessThan": "d06bf78e55d5159c1b00072e606ab924ffbbad35",
              "status": "affected",
              "version": "448f97fba9013ffa13f5dd82febd18836b189499",
              "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": "6.18"
            },
            {
              "lessThan": "6.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.8",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nperf: Fix refcount warning on event-\u003emmap_count increment\n\nWhen calling refcount_inc(\u0026event-\u003emmap_count) inside perf_mmap_rb(), the\nfollowing warning is triggered:\n\n        refcount_t: addition on 0; use-after-free.\n        WARNING: lib/refcount.c:25\n\nPoC:\n\n    struct perf_event_attr attr = {0};\n    int fd = syscall(__NR_perf_event_open, \u0026attr, 0, -1, -1, 0);\n    mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);\n    int victim = syscall(__NR_perf_event_open, \u0026attr, 0, -1, fd,\n                         PERF_FLAG_FD_OUTPUT);\n    mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, victim, 0);\n\nThis occurs when creating a group member event with the flag\nPERF_FLAG_FD_OUTPUT. The group leader should be mmap-ed and then mmap-ing\nthe event triggers the warning.\n\nSince the event has copied the output_event in perf_event_set_output(),\nevent-\u003erb is set. As a result, perf_mmap_rb() calls\nrefcount_inc(\u0026event-\u003emmap_count) when event-\u003emmap_count = 0.\n\nDisallow the case when event-\u003emmap_count = 0. This also prevents two\nevents from updating the same user_page."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-14T15:09:56.237Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/23c0e4bd93d0b250775162faf456470485ac9fc7"
        },
        {
          "url": "https://git.kernel.org/stable/c/d06bf78e55d5159c1b00072e606ab924ffbbad35"
        }
      ],
      "title": "perf: Fix refcount warning on event-\u003emmap_count increment",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23127",
    "datePublished": "2026-02-14T15:09:56.237Z",
    "dateReserved": "2026-01-13T15:37:45.970Z",
    "dateUpdated": "2026-02-14T15:09:56.237Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23127\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-02-14T15:16:07.963\",\"lastModified\":\"2026-02-14T15:16:07.963\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nperf: Fix refcount warning on event-\u003emmap_count increment\\n\\nWhen calling refcount_inc(\u0026event-\u003emmap_count) inside perf_mmap_rb(), the\\nfollowing warning is triggered:\\n\\n        refcount_t: addition on 0; use-after-free.\\n        WARNING: lib/refcount.c:25\\n\\nPoC:\\n\\n    struct perf_event_attr attr = {0};\\n    int fd = syscall(__NR_perf_event_open, \u0026attr, 0, -1, -1, 0);\\n    mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);\\n    int victim = syscall(__NR_perf_event_open, \u0026attr, 0, -1, fd,\\n                         PERF_FLAG_FD_OUTPUT);\\n    mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, victim, 0);\\n\\nThis occurs when creating a group member event with the flag\\nPERF_FLAG_FD_OUTPUT. The group leader should be mmap-ed and then mmap-ing\\nthe event triggers the warning.\\n\\nSince the event has copied the output_event in perf_event_set_output(),\\nevent-\u003erb is set. As a result, perf_mmap_rb() calls\\nrefcount_inc(\u0026event-\u003emmap_count) when event-\u003emmap_count = 0.\\n\\nDisallow the case when event-\u003emmap_count = 0. This also prevents two\\nevents from updating the same user_page.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/23c0e4bd93d0b250775162faf456470485ac9fc7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d06bf78e55d5159c1b00072e606ab924ffbbad35\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}

GHSA-5PM5-3FX7-4F4R

Vulnerability from github – Published: 2026-02-14 15:32 – Updated: 2026-02-14 15:32

Details

In the Linux kernel, the following vulnerability has been resolved:

perf: Fix refcount warning on event->mmap_count increment

When calling refcount_inc(&event->mmap_count) inside perf_mmap_rb(), the following warning is triggered:

    refcount_t: addition on 0; use-after-free.
    WARNING: lib/refcount.c:25

PoC:

struct perf_event_attr attr = {0};
int fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
int victim = syscall(__NR_perf_event_open, &attr, 0, -1, fd,
                     PERF_FLAG_FD_OUTPUT);
mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, victim, 0);

This occurs when creating a group member event with the flag PERF_FLAG_FD_OUTPUT. The group leader should be mmap-ed and then mmap-ing the event triggers the warning.

Since the event has copied the output_event in perf_event_set_output(), event->rb is set. As a result, perf_mmap_rb() calls refcount_inc(&event->mmap_count) when event->mmap_count = 0.

Disallow the case when event->mmap_count = 0. This also prevents two events from updating the same user_page.

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-23127"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-02-14T15:16:07Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nperf: Fix refcount warning on event-\u003emmap_count increment\n\nWhen calling refcount_inc(\u0026event-\u003emmap_count) inside perf_mmap_rb(), the\nfollowing warning is triggered:\n\n        refcount_t: addition on 0; use-after-free.\n        WARNING: lib/refcount.c:25\n\nPoC:\n\n    struct perf_event_attr attr = {0};\n    int fd = syscall(__NR_perf_event_open, \u0026attr, 0, -1, -1, 0);\n    mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);\n    int victim = syscall(__NR_perf_event_open, \u0026attr, 0, -1, fd,\n                         PERF_FLAG_FD_OUTPUT);\n    mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, victim, 0);\n\nThis occurs when creating a group member event with the flag\nPERF_FLAG_FD_OUTPUT. The group leader should be mmap-ed and then mmap-ing\nthe event triggers the warning.\n\nSince the event has copied the output_event in perf_event_set_output(),\nevent-\u003erb is set. As a result, perf_mmap_rb() calls\nrefcount_inc(\u0026event-\u003emmap_count) when event-\u003emmap_count = 0.\n\nDisallow the case when event-\u003emmap_count = 0. This also prevents two\nevents from updating the same user_page.",
  "id": "GHSA-5pm5-3fx7-4f4r",
  "modified": "2026-02-14T15:32:19Z",
  "published": "2026-02-14T15:32:19Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23127"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/23c0e4bd93d0b250775162faf456470485ac9fc7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d06bf78e55d5159c1b00072e606ab924ffbbad35"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

FKIE_CVE-2026-23127

Vulnerability from fkie_nvd - Published: 2026-02-14 15:16 - Updated: 2026-02-14 15:16

Severity ?

Summary

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/23c0e4bd93d0b250775162faf456470485ac9fc7
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/d06bf78e55d5159c1b00072e606ab924ffbbad35

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: Fix refcount warning on event-\u003emmap_count increment\n\nWhen calling refcount_inc(\u0026event-\u003emmap_count) inside perf_mmap_rb(), the\nfollowing warning is triggered:\n\n        refcount_t: addition on 0; use-after-free.\n        WARNING: lib/refcount.c:25\n\nPoC:\n\n    struct perf_event_attr attr = {0};\n    int fd = syscall(__NR_perf_event_open, \u0026attr, 0, -1, -1, 0);\n    mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);\n    int victim = syscall(__NR_perf_event_open, \u0026attr, 0, -1, fd,\n                         PERF_FLAG_FD_OUTPUT);\n    mmap(NULL, 0x3000, PROT_READ | PROT_WRITE, MAP_SHARED, victim, 0);\n\nThis occurs when creating a group member event with the flag\nPERF_FLAG_FD_OUTPUT. The group leader should be mmap-ed and then mmap-ing\nthe event triggers the warning.\n\nSince the event has copied the output_event in perf_event_set_output(),\nevent-\u003erb is set. As a result, perf_mmap_rb() calls\nrefcount_inc(\u0026event-\u003emmap_count) when event-\u003emmap_count = 0.\n\nDisallow the case when event-\u003emmap_count = 0. This also prevents two\nevents from updating the same user_page."
    }
  ],
  "id": "CVE-2026-23127",
  "lastModified": "2026-02-14T15:16:07.963",
  "metrics": {},
  "published": "2026-02-14T15:16:07.963",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/23c0e4bd93d0b250775162faf456470485ac9fc7"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d06bf78e55d5159c1b00072e606ab924ffbbad35"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

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-2026-23127 (GCVE-0-2026-23127)

GHSA-5PM5-3FX7-4F4R

FKIE_CVE-2026-23127

Tags

Sightings

Nomenclature