CVE-2026-80638 (GCVE-0-2026-80638)

Vulnerability from cvelistv5 – Published: 2026-08-28 06:48 – Updated: 2026-08-29 06:21
VLAI
Title
ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent
Summary
In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent [BUG] Unlinking a refcounted file whose refcount tree has leaf blocks triggers a fortify panic due to an out-of-bounds write. [CAUSE] When the last leaf block is removed from a refcount tree, ocfs2_remove_refcount_extent() converts the root back to leaf mode with a bulk memset on &rb->rf_records. rf_records sits in an anonymous union with rf_list. rf_list.l_tree_depth aliases rf_records.rl_count, and is 0 for a single-level tree. With rl_count equal to 0, the memset writes past the 16-byte declared size of rf_records, which the fortify checker catches. [FIX] Replace the bulk memset on &rb->rf_records with a correctly-bounded memset on rl_recs[] alone, after setting rl_count to the correct value.
Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 2f26f58df041bbcf692730ff4d8ab0f250d9670d , < f5255516ec7add3a6d5d37853ad5a9a9ddb14305 (git)
Affected: 2f26f58df041bbcf692730ff4d8ab0f250d9670d , < 1ec3cca2d8b6b9ff6584ca626d4c8918bbf48d44 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 7.1.5 , ≤ 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/ocfs2/refcounttree.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f5255516ec7add3a6d5d37853ad5a9a9ddb14305",
              "status": "affected",
              "version": "2f26f58df041bbcf692730ff4d8ab0f250d9670d",
              "versionType": "git"
            },
            {
              "lessThan": "1ec3cca2d8b6b9ff6584ca626d4c8918bbf48d44",
              "status": "affected",
              "version": "2f26f58df041bbcf692730ff4d8ab0f250d9670d",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/ocfs2/refcounttree.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "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": "7.1.5",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent\n\n[BUG]\nUnlinking a refcounted file whose refcount tree has leaf blocks\ntriggers a fortify panic due to an out-of-bounds write.\n\n[CAUSE]\nWhen the last leaf block is removed from a refcount tree,\nocfs2_remove_refcount_extent() converts the root back to leaf mode\nwith a bulk memset on \u0026rb-\u003erf_records. rf_records sits in an anonymous\nunion with rf_list. rf_list.l_tree_depth aliases rf_records.rl_count,\nand is 0 for a single-level tree. With rl_count equal to 0, the memset\nwrites past the 16-byte declared size of rf_records, which the fortify\nchecker catches.\n\n[FIX]\nReplace the bulk memset on \u0026rb-\u003erf_records with a correctly-bounded\nmemset on rl_recs[] alone, after setting rl_count to the correct value."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - OCFS2 registers NFS export operations and is commonly NFS-exported on shared cluster storage; remote NFS SETATTR/truncate or REMOVE/unlink on refcounted files reaches ocfs2_decrease_refcount() and the vulnerable memset via kernel nfsd.\nAC:L - An attacker can deterministically create refcounted files with multi-block refcount trees via reflink/copy_file_range, then trigger removal of the last leaf through truncate or unlink; syzbot reproduced this reliably without races or victim-specific timing.\nPR:L - Only normal filesystem write permission on the target file or parent directory is required to truncate/unlink refcounted data; no real-root or init-namespace capabilities are needed beyond access to the mounted OCFS2 volume.\nUI:N - Exploitation requires only attacker-initiated filesystem operations (reflink setup, truncate, or unlink) on objects they can write; no additional end-user or administrator interaction beyond routine file access is needed.\nS:U - Impact is confined to kernel/filesystem integrity and availability on systems running OCFS2; it does not cross a VM, container, or IOMMU security boundary into another authority domain.\nC:H - The out-of-bounds memset corrupts refcount-tree metadata within the on-disk block image, which can misdirect subsequent metadata reads and expose stale or cross-file cluster data on shared cluster filesystems.\nI:H - This is an out-of-bounds write (FORTIFY reported a 384-byte write past a 16-byte declared rf_records object) that zeros arbitrary portions of the refcount root block, corrupting filesystem metadata and enabling further memory corruption primitives.\nA:H - The fortify-detected out-of-bounds write triggers a kernel WARNING/panic during refcount-tree cleanup, causing node crash or denial of service on OCFS2 cluster members processing the malicious truncate or unlink."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-29T06:21:38.111Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f5255516ec7add3a6d5d37853ad5a9a9ddb14305"
        },
        {
          "url": "https://git.kernel.org/stable/c/1ec3cca2d8b6b9ff6584ca626d4c8918bbf48d44"
        }
      ],
      "title": "ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80638",
    "datePublished": "2026-08-28T06:48:51.439Z",
    "dateReserved": "2026-08-26T14:34:25.777Z",
    "dateUpdated": "2026-08-29T06:21:38.111Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-80638",
      "date": "2026-09-01",
      "epss": "0.00348",
      "percentile": "0.2764"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-80638\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-28T08:16:48.720\",\"lastModified\":\"2026-08-29T07:16:47.790\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent\\n\\n[BUG]\\nUnlinking a refcounted file whose refcount tree has leaf blocks\\ntriggers a fortify panic due to an out-of-bounds write.\\n\\n[CAUSE]\\nWhen the last leaf block is removed from a refcount tree,\\nocfs2_remove_refcount_extent() converts the root back to leaf mode\\nwith a bulk memset on \u0026rb-\u003erf_records. rf_records sits in an anonymous\\nunion with rf_list. rf_list.l_tree_depth aliases rf_records.rl_count,\\nand is 0 for a single-level tree. With rl_count equal to 0, the memset\\nwrites past the 16-byte declared size of rf_records, which the fortify\\nchecker catches.\\n\\n[FIX]\\nReplace the bulk memset on \u0026rb-\u003erf_records with a correctly-bounded\\nmemset on rl_recs[] alone, after setting rl_count to the correct value.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/ocfs2/refcounttree.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2f26f58df041bbcf692730ff4d8ab0f250d9670d\",\"lessThan\":\"f5255516ec7add3a6d5d37853ad5a9a9ddb14305\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"2f26f58df041bbcf692730ff4d8ab0f250d9670d\",\"lessThan\":\"1ec3cca2d8b6b9ff6584ca626d4c8918bbf48d44\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/ocfs2/refcounttree.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.19\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.19\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":8.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1ec3cca2d8b6b9ff6584ca626d4c8918bbf48d44\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f5255516ec7add3a6d5d37853ad5a9a9ddb14305\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-09-01T07:35:27+00:00",
      "cve": "CVE-2026-80638",
      "id": "CVE-2026-80638",
      "initial_release_date": "2026-08-28T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80638.json",
      "version": "3"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





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.


Detection rules are retrieved from Rulezet.