{
  "cveId": "CVE-2026-92503",
  "url": "https://patchblox.com/security/cve/CVE-2026-92503",
  "summary": "CVE-2026-92503 is fixed in 12 products on 1 platform, first by DEBIAN-CVE-2026-92503, released September 23, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  ext4: fix ABBA deadlock in ext4_xattr_inode_cache_find()  Syzbot/stress-ng reported an ABBA deadlock in ext4 when exercising concurrent xattr workloads (using the ea_inode mount/format option).  The deadlock occurs between the running transaction and the eviction thread: - Task 1 (stress-ng): Holds a reference to a shared mbcache_entry (ce)   and calls ext4_xattr_inode_cache_find() -\u003E ext4_iget() to retrieve   the corresponding EA inode. Since the EA inode is currently being   evicted, ext4_iget() blocks in __wait_on_freeing_inode() waiting for   eviction to complete. - Task 2 (eviction thread): Currently evicting the same EA inode in   ext4_evict_ea_inode(). It calls mb_cache_entry_wait_unused(oe) which   blocks waiting for Task 1 to release the reference to the mbcache_entry.  To break this deadlock, implement a new ext4_iget() configuration flag named EXT4_IGET_NOWAIT. When set, perform a non-blocking lookup of the inode via VFS\u0027s find_inode_nowait() API.  If the inode is currently being evicted (marked with I_FREEING or I_WILL_FREE) or created (I_CREATING), or if it is not present in the VFS inode cache (cache miss), simply skip it (returning -ENOENT) rather than waiting for eviction/creation to complete, breaking the ABBA cycle.  Since we return -ENOENT immediately on a cache miss, we never attempt to allocate a new inode or call iget_locked(), completely eliminating any TOCTOU race window.  If the returned inode is I_NEW, wait for its initialization to clear via wait_on_new_inode(). If initialization fails and the inode is unhashed during wait_on_new_inode() waking up (e.g., due to an I/O read error in another thread), safely drop the reference and return -ENOENT. This unhashed check is executed unconditionally on all cache-hit pathways to properly handle concurrent initialization failures.  Finally, standard validation checks (including is_bad_inode, EXT4_EA_INODE_FL, file_acl, and xattr flags) are executed as normal inside check_igot_inode() to fully guarantee VFS-layer safety.  In ext4_xattr_inode_cache_find(), invoke ext4_iget() with the new EXT4_IGET_NOWAIT flag to perform the non-blocking cache search.",
  "published": "2026-09-17T17:17:52Z",
  "severity": "Moderate",
  "cvss": 5.5,
  "epss": 0.00219,
  "epssPercentile": 0.12499,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-92503",
  "fixes": [
    {
      "platform": "linux",
      "product": "kernel-64kb",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.84.1",
      "fix": "SUSE-SU-2026:4706-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4706-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-azure",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.84.1",
      "fix": "SUSE-SU-2026:4706-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4706-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-default",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.84.1",
      "fix": "SUSE-SU-2026:4706-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4706-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-default-base",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.84.1.150700.17.47.1",
      "fix": "SUSE-SU-2026:4706-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4706-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-docs",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.84.1",
      "fix": "SUSE-SU-2026:4706-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4706-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-livepatch-SLE15-SP7-RT_Update_21",
      "release": "sles 15.7",
      "fixedVersion": "1-150700.1.3.1",
      "fix": "SUSE-SU-2026:4640-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4640-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-livepatch-SLE15-SP7_Update_22",
      "release": "sles 15.7",
      "fixedVersion": "1-150700.15.3.1",
      "fix": "SUSE-SU-2026:4706-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4706-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-obs-build",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.84.1",
      "fix": "SUSE-SU-2026:4706-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4706-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-source",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.84.1",
      "fix": "SUSE-SU-2026:4706-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4706-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-syms",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.84.1",
      "fix": "SUSE-SU-2026:4706-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4706-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "kernel-zfcpdump",
      "release": "sles 15.7",
      "fixedVersion": "6.4.0-150700.53.84.1",
      "fix": "SUSE-SU-2026:4706-1",
      "url": "https://patchblox.com/security/fix/linux/suse-su-2026-4706-1",
      "released": "2026-11-07T00:43:02Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.115-2",
      "fix": "DEBIAN-CVE-2026-92503",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-92503",
      "released": "2026-09-23T19:19:02Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.6-1",
      "fix": "DEBIAN-CVE-2026-92503",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-92503",
      "released": "2026-09-23T19:19:02Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T06:59:42Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}