CVE-2026-89649

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: ceph: bound xattr value length in __build_xattrs() __build_xattrs() decodes the MDS-supplied xattr blob one attribute at a time. For each attribute it reads a 32-bit name length, advances past the name bytes, reads a 32-bit value length, records the value pointer, and advances past the value bytes. The two length fields are read with ceph_decode_32_safe(), but the value bytes themselves are advanced over with a bare "p += len" and no ceph_decode_need() check that "len" bytes remain in the blob. For every attribute except the last, the next iteration's ceph_decode_32_safe() on the following name length implicitly verifies that the previous value did not run past the blob end. The final attribute has no successor, so its decoded value length is never checked against the blob bounds. A malicious or compromised metadata server can set the last attribute's value length larger than the bytes actually present in the blob. The blob is a dedicated kvmalloc() allocation sized to the wire length (ceph_buffer_new() in ceph_fill_inode()). __set_xattr() records the oversized length in xattr->val_len verbatim, and a later getxattr(2) runs memcpy(value, xattr->val, xattr->val_len) into a user-supplied buffer, copying bytes past the end of the allocation back to user space. Impact: a malicious metadata server discloses adjacent kernel heap bytes to a local user via getxattr(2) on a CephFS file. Add the missing ceph_decode_need() so an out-of-bounds value length on the final attribute fails the decode and returns -EIO instead of being stored.

Severity

CRITICAL

CVSS score

9.1 (v3.1)

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-09-11 20:19:50.897000

Last modified

2026-10-19 09:18:02.230000

View original CVE JSON

{
  "id": "CVE-2026-89649",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-09-11T20:19:50.897",
  "lastModified": "2026-10-19T09:18:02.230",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: bound xattr value length in __build_xattrs()\n\n__build_xattrs() decodes the MDS-supplied xattr blob one attribute at a\ntime. For each attribute it reads a 32-bit name length, advances past the\nname bytes, reads a 32-bit value length, records the value pointer, and\nadvances past the value bytes. The two length fields are read with\nceph_decode_32_safe(), but the value bytes themselves are advanced over\nwith a bare \"p += len\" and no ceph_decode_need() check that \"len\" bytes\nremain in the blob.\n\nFor every attribute except the last, the next iteration's\nceph_decode_32_safe() on the following name length implicitly verifies\nthat the previous value did not run past the blob end. The final\nattribute has no successor, so its decoded value length is never checked\nagainst the blob bounds. A malicious or compromised metadata server can\nset the last attribute's value length larger than the bytes actually\npresent in the blob.\n\nThe blob is a dedicated kvmalloc() allocation sized to the wire length\n(ceph_buffer_new() in ceph_fill_inode()). __set_xattr() records the\noversized length in xattr->val_len verbatim, and a later getxattr(2) runs\nmemcpy(value, xattr->val, xattr->val_len) into a user-supplied buffer,\ncopying bytes past the end of the allocation back to user space.\n\nImpact: a malicious metadata server discloses adjacent kernel heap bytes\nto a local user via getxattr(2) on a CephFS file. Add the missing\nceph_decode_need() so an out-of-bounds value length on the final\nattribute fails the decode and returns -EIO instead of being stored."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "fs/ceph/xattr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "355da1eb7a1f91c276b991764e951bbcd8047599",
              "lessThan": "848b80ca6b410f350d08b8ac19a00ef88223f2ea",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "355da1eb7a1f91c276b991764e951bbcd8047599",
              "lessThan": "01e3f19c301d492e12f16b3b463ac14d7cf3ebe7",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "355da1eb7a1f91c276b991764e951bbcd8047599",
              "lessThan": "cb0cd79ae80476d1bc06bd9678484b6736f19588",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "355da1eb7a1f91c276b991764e951bbcd8047599",
              "lessThan": "61f085cb8976c9cebc90e1a8933e4cc1ad8b0fce",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "355da1eb7a1f91c276b991764e951bbcd8047599",
              "lessThan": "38be2f3c41ecaba58bb92dc16603e09ba9fd64f1",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "355da1eb7a1f91c276b991764e951bbcd8047599",
              "lessThan": "1dd356310b1660215f9a3626580bf8b363ef981e",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "355da1eb7a1f91c276b991764e951bbcd8047599",
              "lessThan": "b12b3320c81fd72ab36388fb2445fec9c3038f10",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "355da1eb7a1f91c276b991764e951bbcd8047599",
              "lessThan": "68d541754d6cd3bb98d1fd8314f57e5eb533557d",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "fs/ceph/xattr.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "2.6.34",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "2.6.34",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.10.270",
              "lessThanOrEqual": "5.10.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.15.221",
              "lessThanOrEqual": "5.15.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.188",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.157",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.109",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.50",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2.4",
              "lessThanOrEqual": "7.2.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.3",
              "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:N/UI:N/S:U/C:H/I:N/A:H",
          "baseScore": 9.1,
          "baseSeverity": "CRITICAL",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.2
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-10-16T19:25:12.408770Z",
          "id": "CVE-2026-89649",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/01e3f19c301d492e12f16b3b463ac14d7cf3ebe7",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
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}