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Linux KernelOperating system · Linux

CVE-2026-46052

HIGH · 7.5 CVSS v3.1 Published 2026-05-27
Fix available
A fix is available. Upgrade to 6.6.140 / 6.12.86 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: ceph: only d_add() negative dentries when they are unhashed Ceph can call d_add(dentry, NULL) on a negative dentry that is already present in the primary dcache hash. In the current VFS that is not safe. d_add() goes through __d_add() to __d_rehash(), which unconditionally reinserts dentry->d_hash into the hlist_bl bucket. If the dentry is already hashed, reinserting the same node can corrupt the bucket, including creating a self-loop. Once that happens, __d_lookup() can spin forever in the hlist_bl walk, typically looping only on the d_name.hash mismatch check and eventually triggering RCU stall reports like this one: rcu: INFO: rcu_sched self-detected stall on CPU rcu: 87-....: (2100 ticks this GP) idle=3a4c/1/0x4000000000000000 softirq=25003319/25003319 fqs=829 rcu: (t=2101 jiffies g=79058445 q=698988 ncpus=192) CPU: 87 UID: 2952868916 PID: 3933303 Comm: php-cgi8.3 Not tainted 6.18.17-i1-amd #950 NONE Hardware name: Dell Inc. PowerEdge R7615/0G9DHV, BIOS 1.6.6 09/22/2023 RIP: 0010:__d_lookup+0x46/0xb0 Code: c1 e8 07 48 8d 04 c2 48 8b 00 49 89 fc 49 89 f5 48 89 c3 48 83 e3 fe 48 83 f8 01 77 0f eb 2d 0f 1f 44 00 00 48 8b 1b 48 85 db <74> 20 39 6b 18 75 f3 48 8d 7b 78 e8 ba 85 d0 00 4c 39 63 10 74 1f RSP: 0018:ff745a70c8253898 EFLAGS: 00000282 RAX: ff26e470054cb208 RBX: ff26e470054cb208 RCX: 000000006e958966 RDX: ff26e48267340000 RSI: ff745a70c82539b0 RDI: ff26e458f74655c0 RBP: 000000006e958966 R08: 0000000000000180 R09: 9cd08d909b919a89 R10: ff26e458f74655c0 R11: 0000000000000000 R12: ff26e458f74655c0 R13: ff745a70c82539b0 R14: d0d0d0d0d0d0d0d0 R15: 2f2f2f2f2f2f2f2f FS: 00007f5770896980(0000) GS:ff26e482c5d88000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5764de50c0 CR3: 000000a72abb5001 CR4: 0000000000771ef0 PKRU: 55555554 Call Trace: <TASK> lookup_fast+0x9f/0x100 walk_component+0x1f/0x150 link_path_walk+0x20e/0x3d0 path_lookupat+0x68/0x180 filename_lookup+0xdc/0x1e0 vfs_statx+0x6c/0x140 vfs_fstatat+0x67/0xa0 __do_sys_newfstatat+0x24/0x60 do_syscall_64+0x6a/0x230 entry_SYSCALL_64_after_hwframe+0x76/0x7e This is reachable with reused cached negative dentries. A Ceph lookup or atomic_open can be handed a negative dentry that is already hashed, and fs/ceph/dir.c then hits one of two paths that incorrectly assume "negative" also means "unhashed": - ceph_finish_lookup(): MDS reply is -ENOENT with no trace -> d_add(dentry, NULL) - ceph_lookup(): local ENOENT fast path for a complete directory with shared caps -> d_add(dentry, NULL) Both paths can therefore re-add an already-hashed negative dentry. Ceph already uses the correct pattern elsewhere: ceph_fill_trace() only calls d_add(dn, NULL) for a negative null-dentry reply when d_unhashed(dn) is true. Fix both fs/ceph/dir.c sites the same way: only call d_add() for a negative dentry when it is actually unhashed. If the negative dentry is already hashed, leave it in place and reuse it as-is. This preserves the existing behavior for unhashed dentries while avoiding d_hash list corruption for reused hashed negatives.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 2.6.34.1, < 6.6.140>= 6.7, < 6.12.86>= 6.13, < 6.18.27>= 6.19, < 7.0.4= 2.6.34

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.6.140 / 6.12.86 / 6.18.27 or later
Fixed in 6.6.1406.12.866.18.27
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade to kernel 6.6.140+ (for 6.6.x), 6.12.86+ (for 6.7-6.12.x), 6.18.27+ (for 6.13-6.18.x), or 7.0.4+ (for 6.19-7.0.x)

  1. Identify the currently running Linux kernel version using `uname -r`
  2. Determine which kernel branch your version belongs to (6.6.x, 6.7-6.12.x, 6.13-6.18.x, or 6.19-7.0.x)
  3. For 6.6.x: upgrade to kernel version 6.6.140 or later
  4. For 6.7-6.12.x: upgrade to kernel version 6.12.86 or later
  5. For 6.13-6.18.x: upgrade to kernel version 6.18.27 or later
  6. For 6.19-7.0.x: upgrade to kernel version 7.0.4 or later
  7. Reboot the system to apply the new kernel
  8. Verify the fix is applied by checking the kernel version and confirming the commit is included
Caveat Kernel upgrades may require rebuilding out-of-tree kernel modules; ensure Ceph-related modules are compatible with the new kernel version

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

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