{
  "cveId": "CVE-2026-89767",
  "url": "https://patchblox.com/security/cve/CVE-2026-89767",
  "summary": "CVE-2026-89767 is fixed in 20 products on 1 platform, first by DEBIAN-CVE-2026-89767, released September 23, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  ovl: fix double end_creating() on the casefold-m...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  ovl: fix double end_creating() on the casefold-mismatch path  ovl_create_real() releases the new dentry twice when the casefold consistency check fails.  The S_IFDIR branch calls end_creating() and sets err, then falls through to the common out: label which calls end_creating() on the same dentry again:  \tcase S_IFDIR: \t\tnewdentry = ovl_do_mkdir(ofs, dir, newdentry, attr-\u003Emode); \t\terr = PTR_ERR_OR_ZERO(newdentry); \t\tif (!err \u0026\u0026 ofs-\u003Ecasefold != ovl_dentry_casefolded(newdentry)) { \t\t\tpr_warn_ratelimited(...); \t\t\tend_creating(newdentry);\t/* first */ \t\t\terr = -EINVAL; \t\t} \t\tbreak; \t... \tif (err) \t\tgoto out; \t...  out: \tif (err) { \t\tend_creating(newdentry);\t/* second, same dentry */ \t\treturn ERR_PTR(err); \t}  end_creating() is end_dirop(), which does inode_unlock() on the parent and dput() on the dentry, so the parent directory\u0027s i_rwsem is unlocked twice and the dentry is put twice.  The second unlock releases a lock that is not held, which is what wedges every later creation under that parent, and the second dput() drops a reference that was never taken.  The branch was added by commit dfc7da402ccc (\u0022ovl: Check for casefold consistency when creating new dentries\u0022) as a bare dput(), which already released the reference twice; commit fe497f0759e0 (\u0022VFS: change vfs_mkdir() to unlock on failure.\u0022) converted both sites to end_creating(), adding the double unlock.  This is reachable by an unprivileged user.  The casefold consistency of the layers is validated at mount time in ovl_parse_layer(), and again on every lookup in ovl_lookup_single(), but ofs-\u003Eworkdir is the internal \u0022work\u0022 subdirectory created inside the user-supplied workdir, and that subdirectory is not re-checked.  Marking it casefolded after the mount therefore makes every ovl_create_temp() inherit the wrong state - and that path reaches ovl_create_real() through ovl_start_creating_temp(), which uses start_creating() with a generated name and so never runs the lookup-time check.    unshare -Urm   mount -t tmpfs -o casefold=utf8-12.1.0 tmpfs mnt   mkdir -p mnt/lower/d mnt/upper mnt/work mnt/merged   mount -t overlay ovl -o lowerdir=mnt/lower,\\         upperdir=mnt/upper,workdir=mnt/work mnt/merged   chattr \u002BF mnt/work/work   mkdir mnt/merged/d/sub\t\t# directory copy-up    overlayfs: wrong inherited casefold (work/#5)  and the next copy-up blocks forever on the parent\u0027s i_rwsem:    mkdir           D  start_creating\u002B0x65/0xb0                      ovl_start_creating_temp\u002B0xb0/0xe0 [overlay]                      ovl_create_temp\u002B0xa3/0x1d0 [overlay]                      ovl_copy_up_one\u002B0x1f1c/0x21c0 [overlay]                      ovl_copy_up_flags\u002B0xf5/0x140 [overlay]                      ovl_create_object\u002B0xb7/0x220 [overlay]                      ovl_mkdir\u002B0x23/0x40 [overlay]  Drop the end_creating() from the branch and let out: own the cleanup, which is what every other error path in this function already does.",
  "published": "2026-09-11T20:20:07Z",
  "severity": "high",
  "cvss": 7.8,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
  "epss": 0.00173,
  "epssPercentile": 0.06811,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "bpftool6.18",
      "release": "amzn 2023",
      "fixedVersion": "1:6.18.51-120.162.amzn2023",
      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
      "platform": "linux",
      "product": "bpftool6.18-debuginfo",
      "release": "amzn 2023",
      "fixedVersion": "1:6.18.51-120.162.amzn2023",
      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
      "platform": "linux",
      "product": "kernel-livepatch-6.18.51-120.162",
      "release": "amzn 2023",
      "fixedVersion": "1:1.0-0.amzn2023",
      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "release": "amzn 2023",
      "fixedVersion": "1:6.18.51-120.162.amzn2023",
      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
      "platform": "linux",
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      "release": "amzn 2023",
      "fixedVersion": "1:6.18.51-120.162.amzn2023",
      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
      "platform": "linux",
      "product": "kernel6.18-debuginfo-common-aarch64",
      "release": "amzn 2023",
      "fixedVersion": "1:6.18.51-120.162.amzn2023",
      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "release": "amzn 2023",
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
      "platform": "linux",
      "product": "kernel6.18-devel",
      "release": "amzn 2023",
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
      "platform": "linux",
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
      "platform": "linux",
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      "release": "amzn 2023",
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.6-1",
      "fix": "DEBIAN-CVE-2026-89767",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-89767",
      "released": "2026-09-23T19:19:02Z"
    },
    {
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      "product": "microvm-kernel6.18",
      "release": "amzn 2023",
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
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      "fix": "ALAS2023-2026-3187",
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      "released": "2026-11-07T01:06:52Z"
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
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    {
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
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      "fix": "ALAS2023-2026-3187",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-3187",
      "released": "2026-11-07T01:06:52Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}