CVE-2026-63804 (GCVE-0-2026-63804)

Vulnerability from cvelistv5 – Published: 2026-07-19 12:02 – Updated: 2026-08-17 04:51
VLAI
Title
gfs2: fix use-after-free in gfs2_qd_dealloc
Summary
In the Linux kernel, the following vulnerability has been resolved: gfs2: fix use-after-free in gfs2_qd_dealloc gfs2_qd_dealloc(), called as an RCU callback from gfs2_qd_dispose(), accesses the superblock object sdp through qd->qd_sbd after freeing qd. It does so to decrement sd_quota_count and wake up sd_kill_wait. However, by the time the RCU callback runs, gfs2_put_super() may have already freed sdp via free_sbd(). This can happen when gfs2_quota_cleanup() is called during unmount: it disposes of quota objects via call_rcu() and then waits on sd_kill_wait with a 60-second timeout. If the timeout expires, or if gfs2_gl_hash_clear() triggers additional qd_put() calls that schedule more RCU callbacks after the wait completes, gfs2_put_super() will proceed to free the superblock while RCU callbacks referencing it are still pending. Add an rcu_barrier() before free_sbd() in gfs2_put_super() to ensure all pending RCU callbacks (including gfs2_qd_dealloc) have completed before the superblock is freed.
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 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a475c5dd16e57c570113eccba51955b5df8bb052 , < 4fe388218826df8607ae41a6305df67db08a9093 (git)
Affected: a475c5dd16e57c570113eccba51955b5df8bb052 , < 8745d9f7e1682c39f0a1578895ac74205e2a6757 (git)
Affected: a475c5dd16e57c570113eccba51955b5df8bb052 , < b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0 (git)
Affected: a475c5dd16e57c570113eccba51955b5df8bb052 , < 9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0 (git)
Affected: a475c5dd16e57c570113eccba51955b5df8bb052 , < f9c9ec2c319f843b70ecdf939d48b52d189bc081 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.6
Unaffected: 0 , < 6.6 (semver)
Unaffected: 6.6.144 , ≤ 6.6.* (semver)
Unaffected: 6.12.95 , ≤ 6.12.* (semver)
Unaffected: 6.18.38 , ≤ 6.18.* (semver)
Unaffected: 7.1.3 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/gfs2/super.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "4fe388218826df8607ae41a6305df67db08a9093",
              "status": "affected",
              "version": "a475c5dd16e57c570113eccba51955b5df8bb052",
              "versionType": "git"
            },
            {
              "lessThan": "8745d9f7e1682c39f0a1578895ac74205e2a6757",
              "status": "affected",
              "version": "a475c5dd16e57c570113eccba51955b5df8bb052",
              "versionType": "git"
            },
            {
              "lessThan": "b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0",
              "status": "affected",
              "version": "a475c5dd16e57c570113eccba51955b5df8bb052",
              "versionType": "git"
            },
            {
              "lessThan": "9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0",
              "status": "affected",
              "version": "a475c5dd16e57c570113eccba51955b5df8bb052",
              "versionType": "git"
            },
            {
              "lessThan": "f9c9ec2c319f843b70ecdf939d48b52d189bc081",
              "status": "affected",
              "version": "a475c5dd16e57c570113eccba51955b5df8bb052",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/gfs2/super.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6"
            },
            {
              "lessThan": "6.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.144",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.95",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.38",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.144",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.95",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.38",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.3",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: fix use-after-free in gfs2_qd_dealloc\n\ngfs2_qd_dealloc(), called as an RCU callback from gfs2_qd_dispose(),\naccesses the superblock object sdp through qd-\u003eqd_sbd after freeing qd.\nIt does so to decrement sd_quota_count and wake up sd_kill_wait.\n\nHowever, by the time the RCU callback runs, gfs2_put_super() may have\nalready freed sdp via free_sbd().  This can happen when\ngfs2_quota_cleanup() is called during unmount: it disposes of quota\nobjects via call_rcu() and then waits on sd_kill_wait with a 60-second\ntimeout.  If the timeout expires, or if gfs2_gl_hash_clear() triggers\nadditional qd_put() calls that schedule more RCU callbacks after the\nwait completes, gfs2_put_super() will proceed to free the superblock\nwhile RCU callbacks referencing it are still pending.\n\nAdd an rcu_barrier() before free_sbd() in gfs2_put_super() to ensure\nall pending RCU callbacks (including gfs2_qd_dealloc) have completed\nbefore the superblock is freed."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:51:09.991Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/4fe388218826df8607ae41a6305df67db08a9093"
        },
        {
          "url": "https://git.kernel.org/stable/c/8745d9f7e1682c39f0a1578895ac74205e2a6757"
        },
        {
          "url": "https://git.kernel.org/stable/c/b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0"
        },
        {
          "url": "https://git.kernel.org/stable/c/9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0"
        },
        {
          "url": "https://git.kernel.org/stable/c/f9c9ec2c319f843b70ecdf939d48b52d189bc081"
        }
      ],
      "title": "gfs2: fix use-after-free in gfs2_qd_dealloc",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63804",
    "datePublished": "2026-07-19T12:02:09.111Z",
    "dateReserved": "2026-07-19T07:54:57.013Z",
    "dateUpdated": "2026-08-17T04:51:09.991Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-63804",
      "date": "2026-10-30",
      "epss": "0.00132",
      "percentile": "0.02752"
    },
    "microsoft_vex": {
      "current_release_date": "2026-08-12T23:53:43.000Z",
      "cve": "CVE-2026-63804",
      "id": "msrc_CVE-2026-63804",
      "initial_release_date": "2026-07-20T01:06:55.000Z",
      "product_status:known_not_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "gfs2: fix use-after-free in gfs2_qd_dealloc",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-63804.json",
      "version": "3"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "fs/gfs2/super.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "lessThan": "4fe388218826df8607ae41a6305df67db08a9093",
                    "status": "affected",
                    "version": "a475c5dd16e57c570113eccba51955b5df8bb052",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "8745d9f7e1682c39f0a1578895ac74205e2a6757",
                    "status": "affected",
                    "version": "a475c5dd16e57c570113eccba51955b5df8bb052",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0",
                    "status": "affected",
                    "version": "a475c5dd16e57c570113eccba51955b5df8bb052",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0",
                    "status": "affected",
                    "version": "a475c5dd16e57c570113eccba51955b5df8bb052",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "f9c9ec2c319f843b70ecdf939d48b52d189bc081",
                    "status": "affected",
                    "version": "a475c5dd16e57c570113eccba51955b5df8bb052",
                    "versionType": "git"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "fs/gfs2/super.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "6.6"
                  },
                  {
                    "lessThan": "6.6",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.6.*",
                    "status": "unaffected",
                    "version": "6.6.144",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.12.*",
                    "status": "unaffected",
                    "version": "6.12.95",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.18.*",
                    "status": "unaffected",
                    "version": "6.18.38",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "7.1.*",
                    "status": "unaffected",
                    "version": "7.1.3",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.2",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "configurations": [
          {
            "nodes": [
              {
                "cpeMatch": [
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "EB06F04F-FCFC-49B0-8B6C-FE1EA3A596E1",
                    "versionEndExcluding": "6.6.144",
                    "versionStartIncluding": "6.6",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "4E206B86-E0E3-4394-A93F-39F2D50A8AA8",
                    "versionEndExcluding": "6.12.95",
                    "versionStartIncluding": "6.7",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "FA591B28-5D62-449E-BDBE-3C9391BF070A",
                    "versionEndExcluding": "6.18.38",
                    "versionStartIncluding": "6.13",
                    "vulnerable": true
                  },
                  {
                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                    "matchCriteriaId": "9526B150-E2B3-4C6F-8AE5-1AF92B75AD9E",
                    "versionEndExcluding": "7.1.3",
                    "versionStartIncluding": "6.19",
                    "vulnerable": true
                  }
                ],
                "negate": false,
                "operator": "OR"
              }
            ]
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: fix use-after-free in gfs2_qd_dealloc\n\ngfs2_qd_dealloc(), called as an RCU callback from gfs2_qd_dispose(),\naccesses the superblock object sdp through qd-\u003eqd_sbd after freeing qd.\nIt does so to decrement sd_quota_count and wake up sd_kill_wait.\n\nHowever, by the time the RCU callback runs, gfs2_put_super() may have\nalready freed sdp via free_sbd().  This can happen when\ngfs2_quota_cleanup() is called during unmount: it disposes of quota\nobjects via call_rcu() and then waits on sd_kill_wait with a 60-second\ntimeout.  If the timeout expires, or if gfs2_gl_hash_clear() triggers\nadditional qd_put() calls that schedule more RCU callbacks after the\nwait completes, gfs2_put_super() will proceed to free the superblock\nwhile RCU callbacks referencing it are still pending.\n\nAdd an rcu_barrier() before free_sbd() in gfs2_put_super() to ensure\nall pending RCU callbacks (including gfs2_qd_dealloc) have completed\nbefore the superblock is freed."
          }
        ],
        "id": "CVE-2026-63804",
        "lastModified": "2026-08-17T05:17:17.033",
        "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": "nvd@nist.gov",
              "type": "Primary"
            }
          ]
        },
        "published": "2026-07-19T12:16:53.120",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/4fe388218826df8607ae41a6305df67db08a9093"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/8745d9f7e1682c39f0a1578895ac74205e2a6757"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/9d0d5ba20cad661f7f287d4c66d2c19022ce2fd0"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/b85ef03f726b15047a6fa6d11b639bdf6c0ee4f0"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
              "Patch"
            ],
            "url": "https://git.kernel.org/stable/c/f9c9ec2c319f843b70ecdf939d48b52d189bc081"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Analyzed",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-416"
              }
            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-30T05:49:35+00:00",
      "cve": "CVE-2026-63804",
      "id": "CVE-2026-63804",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "197",
      "product_status:known_not_affected": "79",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: gfs2: fix use-after-free in gfs2_qd_dealloc",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63804.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-10-15T14:52:04Z",
      "cve": "CVE-2026-63804",
      "id": "CVE-2026-63804",
      "initial_release_date": "2026-07-19T17:35:01Z",
      "product_status:known_affected": "186",
      "product_status:known_not_affected": "161",
      "product_status:recommended": "149",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-63804",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-63804.json",
      "version": "8"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    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.