# CVE-2026-43071: dcache: Limit the minimal number of bucket to two

> An out-of-bounds read in the Linux kernel dcache occurs when dhash_entries is set to one, potentially causing a crash or information leak.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-43071, DEBIAN-CVE-2026-43071, GHSA-977x-crv2-w57m, ROOT-OS-DEBIAN-11-CVE-2026-43071, ROOT-OS-DEBIAN-12-CVE-2026-43071, ROOT-OS-UBUNTU-2204-CVE-2026-43071, ROOT-OS-UBUNTU-2404-CVE-2026-43071, UBUNTU-CVE-2026-43071

## What is CVE-2026-43071?

CVE-2026-43071 is a critical memory corruption vulnerability in Linux kernel, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

dcache: Limit the minimal number of bucket to two

There is an OOB read problem on dentry_hashtable when user sets
'dhash_entries=1':
  BUG: unable to handle page fault for address: ffff888b30b774b0
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  Oops: Oops: 0000 [#1] SMP PTI
  RIP: 0010:__d_lookup+0x56/0x120
   Call Trace:
    d_lookup.cold+0x16/0x5d
    lookup_dcache+0x27/0xf0
    lookup_one_qstr_excl+0x2a/0x180
    start_dirop+0x55/0xa0
    simple_start_creating+0x8d/0xa0
    debugfs_start_creating+0x8c/0x180
    debugfs_create_dir+0x1d/0x1c0
    pinctrl_init+0x6d/0x140
    do_one_initcall+0x6d/0x3d0
    kernel_init_freeable+0x39f/0x460
    kernel_init+0x2a/0x260

There will be only one bucket in dentry_hashtable when dhash_entries is
set as one, and d_hash_shift is calculated as 32 by dcache_init(). Then,
following process will access more than one buckets(which memory region
is not allocated) in dentry_hashtable:
 d_lookup
  b = d_hash(hash)
    dentry_hashtable + ((u32)hashlen >> d_hash_shift)
    // The C standard defines the behavior of right shift amounts
    // exceeding the bit width of the operand as undefined. The
    // result of '(u32)hashlen >> d_hash_shift' becomes 'hashlen',
    // so 'b' will point to an unallocated memory region.
  hlist_bl_for_each_entry_rcu(b)
   hlist_bl_first_rcu(head)
    h->first  // read OOB!

Fix it by limiting the minimal number of dentry_hashtable bucket to two,
so that 'd_hash_shift' won't exceeds the bit width of type u32.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-43071?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43071?

Apply the vendor's patch.

## Is CVE-2026-43071 being exploited?

There is no known exploitation of CVE-2026-43071 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43071 and fix it if it is affected.

What it is: CVE-2026-43071 is a critical memory corruption vulnerability in Linux kernel, published on 5 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-43071 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-43071/ (Markdown: https://insights.sbomify.com/CVE-2026-43071/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43071
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43071
- OSV: https://osv.dev/vulnerability/CVE-2026-43071

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43071/
Summaries are generated and may contain mistakes; the official description above is the record.