Vulnerability-Lookup

FKIE_CVE-2026-98543

Vulnerability from fkie_nvd - Published: 2026-10-18 16:17 - Updated: 2026-10-24 14:16

Severity

7.3 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir bpf_lsm_has_d_inode_locked() makes the verifier rewrite bpf_[set|remove]_dentry_xattr() to the _locked variants, which assume that the caller already holds the inode's i_rwsem. The path_unlink and path_rmdir hooks are listed, but security_path_unlink() and security_path_rmdir() run before vfs_unlink()/vfs_rmdir() take the victim inode's i_rwsem, so a sleepable BPF LSM program attached to either hook mutates the victim's xattrs without the lock held. Drop the two path hooks from d_inode_locked_hooks so that the verifier keeps the locking bpf_[set|remove]_dentry_xattr() variants, which take the lock themselves.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/35d442ed1f86465e49df3119fb898f985186db13
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/640d37fbd34d03af727dbc567f48c0203d1de6b4
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/7504b677c4370c9e4b153c553ff8831c093b1ff6

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/bpf_fs_kfuncs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "7504b677c4370c9e4b153c553ff8831c093b1ff6",
              "status": "affected",
              "version": "56467292794b800164df20c076c409ac548e56ec",
              "versionType": "git"
            },
            {
              "lessThan": "640d37fbd34d03af727dbc567f48c0203d1de6b4",
              "status": "affected",
              "version": "56467292794b800164df20c076c409ac548e56ec",
              "versionType": "git"
            },
            {
              "lessThan": "35d442ed1f86465e49df3119fb898f985186db13",
              "status": "affected",
              "version": "56467292794b800164df20c076c409ac548e56ec",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/bpf_fs_kfuncs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "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\nbpf: fs/xattr: don\u0027t assume the inode is locked in path_unlink/path_rmdir\n\nbpf_lsm_has_d_inode_locked() makes the verifier rewrite\nbpf_[set|remove]_dentry_xattr() to the _locked variants, which assume\nthat the caller already holds the inode\u0027s i_rwsem.  The path_unlink and\npath_rmdir hooks are listed, but security_path_unlink() and\nsecurity_path_rmdir() run before vfs_unlink()/vfs_rmdir() take the\nvictim inode\u0027s i_rwsem, so a sleepable BPF LSM program attached to\neither hook mutates the victim\u0027s xattrs without the lock held.\n\nDrop the two path hooks from d_inode_locked_hooks so that the verifier\nkeeps the locking bpf_[set|remove]_dentry_xattr() variants, which take\nthe lock themselves."
    }
  ],
  "id": "CVE-2026-98543",
  "lastModified": "2026-10-24T14:16:46.803",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.3,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "LOW",
          "privilegesRequired": "LOW",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.0,
        "impactScore": 4.7,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-10-18T16:17:06.200",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/35d442ed1f86465e49df3119fb898f985186db13"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/640d37fbd34d03af727dbc567f48c0203d1de6b4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7504b677c4370c9e4b153c553ff8831c093b1ff6"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-98543 (GCVE-0-2026-98543)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:18 – Updated: 2026-10-24 14:09

Title

bpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir

Summary

Severity

7.3 (High)


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

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6639 records in the last 180 days details

References

3 references

URL	Tags
https://git.kernel.org/stable/c/7504b677c4370c9e4…
https://git.kernel.org/stable/c/640d37fbd34d03af7…
https://git.kernel.org/stable/c/35d442ed1f86465e4…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 56467292794b800164df20c076c409ac548e56ec , < 7504b677c4370c9e4b153c553ff8831c093b1ff6 (git) Affected: 56467292794b800164df20c076c409ac548e56ec , < 640d37fbd34d03af727dbc567f48c0203d1de6b4 (git) Affected: 56467292794b800164df20c076c409ac548e56ec , < 35d442ed1f86465e49df3119fb898f985186db13 (git)
Linux	Linux	Affected: 6.15 Unaffected: 0 , < 6.15 (semver) Unaffected: 6.18.55 , ≤ 6.18.* (semver) Unaffected: 7.2.9 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/bpf_fs_kfuncs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "7504b677c4370c9e4b153c553ff8831c093b1ff6",
              "status": "affected",
              "version": "56467292794b800164df20c076c409ac548e56ec",
              "versionType": "git"
            },
            {
              "lessThan": "640d37fbd34d03af727dbc567f48c0203d1de6b4",
              "status": "affected",
              "version": "56467292794b800164df20c076c409ac548e56ec",
              "versionType": "git"
            },
            {
              "lessThan": "35d442ed1f86465e49df3119fb898f985186db13",
              "status": "affected",
              "version": "56467292794b800164df20c076c409ac548e56ec",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/bpf_fs_kfuncs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.55",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.9",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: fs/xattr: don\u0027t assume the inode is locked in path_unlink/path_rmdir\n\nbpf_lsm_has_d_inode_locked() makes the verifier rewrite\nbpf_[set|remove]_dentry_xattr() to the _locked variants, which assume\nthat the caller already holds the inode\u0027s i_rwsem.  The path_unlink and\npath_rmdir hooks are listed, but security_path_unlink() and\nsecurity_path_rmdir() run before vfs_unlink()/vfs_rmdir() take the\nvictim inode\u0027s i_rwsem, so a sleepable BPF LSM program attached to\neither hook mutates the victim\u0027s xattrs without the lock held.\n\nDrop the two path hooks from d_inode_locked_hooks so that the verifier\nkeeps the locking bpf_[set|remove]_dentry_xattr() variants, which take\nthe lock themselves."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.3,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - unlink(2)/unlinkat(2)/rmdir(2) reach filename_unlinkat()/filename_rmdir() -\u003e security_path_unlink()/security_path_rmdir() -\u003e bpf_lsm_path_*(); vulnerable bpf_lsm_has_d_inode_locked() classification makes the verifier redirect bpf_[set|remove]_dentry_xattr() to _locked functions. The trigger enters locally, not via a protocol.\nAC:L - On UBIFS, one invocation deterministically fails ubifs_xattr_set()/ubifs_xattr_remove()\u0027s inode_is_locked() assertion; for races, the attacker can unlink two hardlinks in different parents concurrently, so separate parent locks do not serialize the same victim. No condition is outside the attacker\u0027s control.\nPR:L - bpf_prog_load() gates BPF_PROG_TYPE_LSM on bpf_token_capable(CAP_BPF) and CAP_PERFMON. A delegated bpffs token makes those ns_capable(token-\u003euserns, ...) checks, so a namespace-confined non-admin can load and attach the sleepable path hook; without delegation, init-namespace capabilities are required.\nUI:N - The attacker loads and attaches the BPF LSM program, then invokes unlinkat(2) or rmdir(2) on an object it can modify; no victim must mount media, open a file, or perform another action.\nS:C - With bpffs token delegation, a task confined to the token\u0027s user namespace can run the faulty BPF LSM program in the host kernel and force a shared host UBIFS read-only, crossing the container or sandbox availability boundary.\nC:N - Neither affected helper returns filesystem or kernel data: bpf_set_dentry_xattr_locked() only passes a verifier-bounded dynptr to __vfs_setxattr(), and the remove helper has no output. The missing i_rwsem is a mutation-ordering flaw, with no demonstrated OOB read, UAF, or disclosure path.\nI:L - btrfs_setxattr() explicitly relies on the inode lock to exclude a concurrent delete between its XATTR_REPLACE lookup and insert; this bug removes that exclusion, so concurrent path_unlink hooks can recreate or lose security.bpf.* metadata. Btrfs tree locking shows no arbitrary-memory-write primitive, limiting integrity impact.\nA:H - ubifs_xattr_set(..., check_lock=true) and ubifs_xattr_remove() assert inode_is_locked(); default ASSACT_RO calls ubifs_ro_mode(), sets SB_RDONLY, and denies later writes. One path hook calling the mis-selected _locked helper can therefore make a mounted UBIFS lose write availability."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:09:20.159Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/7504b677c4370c9e4b153c553ff8831c093b1ff6"
        },
        {
          "url": "https://git.kernel.org/stable/c/640d37fbd34d03af727dbc567f48c0203d1de6b4"
        },
        {
          "url": "https://git.kernel.org/stable/c/35d442ed1f86465e49df3119fb898f985186db13"
        }
      ],
      "title": "bpf: fs/xattr: don\u0027t assume the inode is locked in path_unlink/path_rmdir",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98543",
    "datePublished": "2026-10-18T15:18:10.823Z",
    "dateReserved": "2026-09-25T10:25:14.356Z",
    "dateUpdated": "2026-10-24T14:09:20.159Z",
    "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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order 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.

Publication & reservation Sightings KEV catalogs Other timestamps

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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.

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