Vulnerability-Lookup

FKIE_CVE-2026-90326

Vulnerability from fkie_nvd - Published: 2026-09-17 17:17 - Updated: 2026-09-18 18:17

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: blk-cgroup: fix race between policy activation and blkg destruction When switching an IO scheduler on a block device, blkcg_activate_policy() allocates blkg_policy_data (pd) for all blkgs attached to the queue. However, blkcg_activate_policy() may race with concurrent blkcg deletion, leading to use-after-free and memory leak issues. The use-after-free occurs in the following race: T1 (blkcg_activate_policy): - Successfully allocates pd for blkg1 (loop0->queue, blkcgA) - Fails to allocate pd for blkg2 (loop0->queue, blkcgB) - Enters the enomem rollback path to release blkg1 resources T2 (blkcg deletion): - blkcgA is deleted concurrently - blkg1 is freed via blkg_free_workfn() - blkg1->pd is freed T1 (continued): - Rollback path accesses blkg1->pd->online after pd is freed - Triggers use-after-free In addition, blkg_free_workfn() frees pd before removing the blkg from q->blkg_list. This allows blkcg_activate_policy() to allocate a new pd for a blkg that is being destroyed, leaving the newly allocated pd unreachable when the blkg is finally freed. Fix these races by extending blkcg_mutex coverage to serialize blkcg_activate_policy() rollback and blkg destruction, ensuring pd lifecycle is synchronized with blkg list visibility.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/083b58373463a6e5ee60ecb135269348f68ad7df
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/5313d4d41739b0cb63000747c97bb1217ac45f3e
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/ac34e655dffa74349d885a43d098115336f53842
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/b5dae1cd0d8368b4338430ff93403df67f0b8bcc

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "block/blk-cgroup.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b5dae1cd0d8368b4338430ff93403df67f0b8bcc",
              "status": "affected",
              "version": "81c1188905f88b77743d1fdeeedfc8cb7b67787d",
              "versionType": "git"
            },
            {
              "lessThan": "083b58373463a6e5ee60ecb135269348f68ad7df",
              "status": "affected",
              "version": "bfe46d2efe46c5c952f982e2ca94fe2ec5e58e2a",
              "versionType": "git"
            },
            {
              "lessThan": "ac34e655dffa74349d885a43d098115336f53842",
              "status": "affected",
              "version": "f1c006f1c6850c14040f8337753a63119bba39b9",
              "versionType": "git"
            },
            {
              "lessThan": "2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd",
              "status": "affected",
              "version": "f1c006f1c6850c14040f8337753a63119bba39b9",
              "versionType": "git"
            },
            {
              "lessThan": "5313d4d41739b0cb63000747c97bb1217ac45f3e",
              "status": "affected",
              "version": "f1c006f1c6850c14040f8337753a63119bba39b9",
              "versionType": "git"
            },
            {
              "lessThan": "6.1.17",
              "status": "affected",
              "version": "6.1.16",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2.4",
              "status": "affected",
              "version": "6.2.3",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "block/blk-cgroup.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.3"
            },
            {
              "lessThan": "6.3",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.17",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.2.*",
              "status": "unaffected",
              "version": "6.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: fix race between policy activation and blkg destruction\n\nWhen switching an IO scheduler on a block device, blkcg_activate_policy()\nallocates blkg_policy_data (pd) for all blkgs attached to the queue.\nHowever, blkcg_activate_policy() may race with concurrent blkcg deletion,\nleading to use-after-free and memory leak issues.\n\nThe use-after-free occurs in the following race:\n\nT1 (blkcg_activate_policy):\n  - Successfully allocates pd for blkg1 (loop0-\u003equeue, blkcgA)\n  - Fails to allocate pd for blkg2 (loop0-\u003equeue, blkcgB)\n  - Enters the enomem rollback path to release blkg1 resources\n\nT2 (blkcg deletion):\n  - blkcgA is deleted concurrently\n  - blkg1 is freed via blkg_free_workfn()\n  - blkg1-\u003epd is freed\n\nT1 (continued):\n  - Rollback path accesses blkg1-\u003epd-\u003eonline after pd is freed\n  - Triggers use-after-free\n\nIn addition, blkg_free_workfn() frees pd before removing the blkg from\nq-\u003eblkg_list. This allows blkcg_activate_policy() to allocate a new pd\nfor a blkg that is being destroyed, leaving the newly allocated pd\nunreachable when the blkg is finally freed.\n\nFix these races by extending blkcg_mutex coverage to serialize\nblkcg_activate_policy() rollback and blkg destruction, ensuring pd\nlifecycle is synchronized with blkg list visibility."
    }
  ],
  "id": "CVE-2026-90326",
  "lastModified": "2026-09-18T18:17:54.130",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-17T17:17:30.673",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/083b58373463a6e5ee60ecb135269348f68ad7df"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5313d4d41739b0cb63000747c97bb1217ac45f3e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ac34e655dffa74349d885a43d098115336f53842"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b5dae1cd0d8368b4338430ff93403df67f0b8bcc"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-90326 (GCVE-0-2026-90326)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:08 – Updated: 2026-09-18 17:54

Title

blk-cgroup: fix race between policy activation and blkg destruction

Summary

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux CNA under the mitre root

CNA scorecard D 54/100 over 6633 records in the last 180 days details

References

5 references

URL	Tags
https://git.kernel.org/stable/c/b5dae1cd0d8368b43…
https://git.kernel.org/stable/c/083b58373463a6e5e…
https://git.kernel.org/stable/c/ac34e655dffa74349…
https://git.kernel.org/stable/c/2cf9f50a38c1839e5…
https://git.kernel.org/stable/c/5313d4d41739b0cb6…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 81c1188905f88b77743d1fdeeedfc8cb7b67787d , < b5dae1cd0d8368b4338430ff93403df67f0b8bcc (git) Affected: bfe46d2efe46c5c952f982e2ca94fe2ec5e58e2a , < 083b58373463a6e5ee60ecb135269348f68ad7df (git) Affected: f1c006f1c6850c14040f8337753a63119bba39b9 , < ac34e655dffa74349d885a43d098115336f53842 (git) Affected: f1c006f1c6850c14040f8337753a63119bba39b9 , < 2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd (git) Affected: f1c006f1c6850c14040f8337753a63119bba39b9 , < 5313d4d41739b0cb63000747c97bb1217ac45f3e (git) Affected: 6.1.16 , < 6.1.17 (semver) Affected: 6.2.3 , < 6.2.4 (semver)
Linux	Linux	Affected: 6.3 Unaffected: 0 , < 6.3 (semver) Unaffected: 6.1.17 , ≤ 6.1.* (semver) Unaffected: 6.2.4 , ≤ 6.2.* (semver) Unaffected: 6.18.52 , ≤ 6.18.* (semver) Unaffected: 7.2.6 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "block/blk-cgroup.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b5dae1cd0d8368b4338430ff93403df67f0b8bcc",
              "status": "affected",
              "version": "81c1188905f88b77743d1fdeeedfc8cb7b67787d",
              "versionType": "git"
            },
            {
              "lessThan": "083b58373463a6e5ee60ecb135269348f68ad7df",
              "status": "affected",
              "version": "bfe46d2efe46c5c952f982e2ca94fe2ec5e58e2a",
              "versionType": "git"
            },
            {
              "lessThan": "ac34e655dffa74349d885a43d098115336f53842",
              "status": "affected",
              "version": "f1c006f1c6850c14040f8337753a63119bba39b9",
              "versionType": "git"
            },
            {
              "lessThan": "2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd",
              "status": "affected",
              "version": "f1c006f1c6850c14040f8337753a63119bba39b9",
              "versionType": "git"
            },
            {
              "lessThan": "5313d4d41739b0cb63000747c97bb1217ac45f3e",
              "status": "affected",
              "version": "f1c006f1c6850c14040f8337753a63119bba39b9",
              "versionType": "git"
            },
            {
              "lessThan": "6.1.17",
              "status": "affected",
              "version": "6.1.16",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2.4",
              "status": "affected",
              "version": "6.2.3",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "block/blk-cgroup.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.3"
            },
            {
              "lessThan": "6.3",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.17",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.2.*",
              "status": "unaffected",
              "version": "6.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.17",
                  "versionStartIncluding": "6.1.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.2.4",
                  "versionStartIncluding": "6.2.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.52",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.6",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "6.3",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: fix race between policy activation and blkg destruction\n\nWhen switching an IO scheduler on a block device, blkcg_activate_policy()\nallocates blkg_policy_data (pd) for all blkgs attached to the queue.\nHowever, blkcg_activate_policy() may race with concurrent blkcg deletion,\nleading to use-after-free and memory leak issues.\n\nThe use-after-free occurs in the following race:\n\nT1 (blkcg_activate_policy):\n  - Successfully allocates pd for blkg1 (loop0-\u003equeue, blkcgA)\n  - Fails to allocate pd for blkg2 (loop0-\u003equeue, blkcgB)\n  - Enters the enomem rollback path to release blkg1 resources\n\nT2 (blkcg deletion):\n  - blkcgA is deleted concurrently\n  - blkg1 is freed via blkg_free_workfn()\n  - blkg1-\u003epd is freed\n\nT1 (continued):\n  - Rollback path accesses blkg1-\u003epd-\u003eonline after pd is freed\n  - Triggers use-after-free\n\nIn addition, blkg_free_workfn() frees pd before removing the blkg from\nq-\u003eblkg_list. This allows blkcg_activate_policy() to allocate a new pd\nfor a blkg that is being destroyed, leaving the newly allocated pd\nunreachable when the blkg is finally freed.\n\nFix these races by extending blkcg_mutex coverage to serialize\nblkcg_activate_policy() rollback and blkg destruction, ensuring pd\nlifecycle is synchronized with blkg list visibility."
        }
      ],
      "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 triggering operations are local cgroupfs writes: tg_set_limit() (io.max) or iolatency_set_limit() (io.latency) call blk_throtl_init()/blk_iolatency_init() then blkcg_activate_policy(), while cgroup_rmdir() runs blkcg_css_offline() into blkg_free_workfn(); elv_iosched_store() is an alternate local sysfs path. No remote protocol carries the race inputs.\nAC:L - The attacker drives both sides: one thread writes io.max/io.latency so blkcg_activate_policy() attaches pd without q-\u003eblkcg_mutex, while another rmdirs sibling blkcgs so blkg_free_workfn() calls pd_free_fn() on the same blkg-\u003epd[] before list_del. That interleaving does not depend on GFP_KERNEL failure; the documented enomem rollback UAF on pd-\u003eonline is an extra window the attacker can retry.\nPR:L - tg_set_limit() and iolatency_set_limit() have no capable() check; io.max/io.latency are CFTYPE_NOT_ON_ROOT S_IWUSR files, and blkg_conf_open_bdev() uses blkdev_get_no_open() with no device permission check. A delegated cgroup-v2 subtree owner (typical systemd user slice or rootless container) can write those files and rmdir child cgroups; scheduler sysfs is a stricter alternate path.\nUI:N - The attacker writes io.max/io.latency in cgroups they own and rmdirs those cgroups themselves; no other user must mount a device, open a file, or otherwise participate.\nS:U - The UAF corrupts kernel blkg_policy_data (throtl_grp/iolatency_grp) in the host io controller; impact stays in the kernel\u0027s authority and does not cross a VM, IOMMU, or other security boundary.\nC:H - blkg_free_workfn() frees blkg-\u003epd[] while the object remains on q-\u003eblkg_list, so blkcg_activate_policy()\u0027s enomem path reads pd-\u003eonline and pd_offline_fn() (throtl_pd_offline()/tg_flush_bios()) walks the freed throtl_grp; spraying the slab reclaims that object for an arbitrary kernel read.\nI:H - The same freed pd is written (pd-\u003eonline = false) and passed to pol-\u003epd_free_fn() again (throtl_pd_free() does timer_delete_sync() and call_rcu()), a double-free of throtl_grp/iolatency_grp that yields a kernel write/control-flow primitive.\nA:H - Use-after-free and double-free of blkg_policy_data in blkcg_activate_policy() versus blkg_free_workfn() oops/panic the kernel even when not turned into a full memory primitive."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-18T17:54:39.274Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/b5dae1cd0d8368b4338430ff93403df67f0b8bcc"
        },
        {
          "url": "https://git.kernel.org/stable/c/083b58373463a6e5ee60ecb135269348f68ad7df"
        },
        {
          "url": "https://git.kernel.org/stable/c/ac34e655dffa74349d885a43d098115336f53842"
        },
        {
          "url": "https://git.kernel.org/stable/c/2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd"
        },
        {
          "url": "https://git.kernel.org/stable/c/5313d4d41739b0cb63000747c97bb1217ac45f3e"
        }
      ],
      "title": "blk-cgroup: fix race between policy activation and blkg destruction",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90326",
    "datePublished": "2026-09-17T16:08:41.374Z",
    "dateReserved": "2026-09-11T19:38:34.802Z",
    "dateUpdated": "2026-09-18T17:54:39.274Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

FKIE_CVE-2026-90326

CVE-2026-90326 (GCVE-0-2026-90326)

Tags

Sightings

Nomenclature

Related by attack behaviour