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CVE-2026-89697 (GCVE-0-2026-89697)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:46 – Updated: 2026-09-14 12:02
VLAI
Title
nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr() The BOTH_TIME_SET branch calls fh_verify() early so setattr_prepare() can inspect the dentry. This causes nfsd_setattr() to skip fh_want_write(), so notify_change() runs without a mount write reference. Add the missing fh_want_write() call after the early fh_verify().
Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 3eec9d791968c177a4a8cda9af5c04f79dae09cb (git)
Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 9229d824b938f4fb0ea7a5dddade51735e6fe6f9 (git)
Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 2150305134889fb2fc25228d35353bd2f6f29500 (git)
Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < d823bf9285cdf4514873b85ab5a888878dd4e8f4 (git)
Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 15ca3b64a69caa6194bed8f98a20ed90a11c11dd (git)
Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 533964d420d385e11b08dd4c56c66ef5dcccaf08 (git)
Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < c4a409b86a92815181a8e9395c6bf1696ad19175 (git)
Affected: cc265089ce1b176dde963c74b53593446ee7f99a , < 4e475be769aa9f7a2c1ce55a2b8592cfccacddcc (git)
Affected: 1cb57d81cf20fe24b9e2e1daf57bfbdc24b77cd8 (git)
Affected: 3.18.46 , < 3.19 (semver)
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Linux Linux Affected: 4.2
Unaffected: 0 , < 4.2 (semver)
Unaffected: 5.10.270 , ≤ 5.10.* (semver)
Unaffected: 5.15.221 , ≤ 5.15.* (semver)
Unaffected: 6.1.188 , ≤ 6.1.* (semver)
Unaffected: 6.6.157 , ≤ 6.6.* (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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              "value": "AV:N - The bug is in nfsd_proc_setattr(), the in-kernel NFSv2 SETATTR handler. A remote client reaches it by sending an NFSv2 SETATTR RPC over TCP/UDP port 2049 with both atime and mtime set, so no local access to the server is required.\nAC:L - Crafting SETATTR with ATTR_ATIME_SET|ATTR_MTIME_SET and equal timestamps deterministically takes the early fh_verify() path so nfsd_setattr() skips fh_want_write(). The attacker fully controls the RPC; no race or uninfluenced memory layout is required.\nPR:N - Default nfsd exports accept AUTH_SYS and AUTH_NULL with no cryptographic authentication, so the client asserts uid/gid. Any host permitted by the export list can issue SETATTR; this matches prior nfsd CNA scoring as PR:N.\nUI:N - The attacking NFS client issues the SETATTR RPC itself. No administrator or end-user action on the server is required.\nS:U - notify_change() without a mount write reference affects only the exported filesystem in the same kernel security authority. No VM, IOMMU, or sandbox boundary is crossed.\nC:N - The defect is a missing mnt_want_write()/sb_start_write() around notify_change() and commit_metadata(). It does not leak kernel memory, pointers, or file contents beyond ordinary authorized NFS access.\nI:H - nfsd_permission\u0027s read-only check does not cover freeze state, so SETATTR including ATTR_SIZE truncate, mode, and ownership updates proceeds on a frozen export and in a remount-ro race, letting a client mutate files and corrupt snapshots when writes should be blocked.\nA:H - Skipping freeze protection lets setattr run during fsfreeze, which can deadlock (inode_lock versus sb_start_write ordering), trigger filesystem withdraw/asserts such as GFS2 adding buffers while frozen, and hang or crash the nfsd thread."
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          }
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                "confidentialityImpact": "NONE",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
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        "vulnStatus": "Received"
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      "initial_release_date": "2026-09-11T00:00:00+00:00",
      "product_status:known_affected": "91",
      "product_status:known_not_affected": "185",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: nfsd: add fh_want_write() for early-verified SETATTR in nfsd_proc_setattr()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89697.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-15T23:59:59Z",
      "cve": "CVE-2026-89697",
      "id": "CVE-2026-89697",
      "initial_release_date": "2026-09-12T16:23:31Z",
      "product_status:known_affected": "349",
      "product_status:known_not_affected": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89697",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-89697.json",
      "version": "4"
    }
  }
}



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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.


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.