Status: UPDATED | Advisory ID: CVE-2026-43071
| CVE | CVE-2026-43071 |
| CVSS Score / Version | 9.1 (Critical) / CVSS v3.1 |
| Updated | 2026-09-08 |
| CVSS Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H |
| CVSS Prose | attack vector is network; attack complexity is low; privileges required is none; user interaction is none; scope is unchanged; confidentiality impact is high; integrity impact is none; availability impact is high. |
| Affected products | Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP, Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP, and Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP |
| Classified as | CWE-125 (Out-of-bounds Read) |
| Vendor | Product | Affected Versions | Patch Status |
|---|---|---|---|
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP | ||
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP | ||
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP |
| Subsystems | General OT |
| Sectors | Multiple |
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. (NVD)
Monitor Siemens's web page for any future patch releases.
| Source | Reference |
|---|---|
| NVD | https://nvd.nist.gov/vuln/detail/CVE-2026-43071 |
| CVE | https://www.cve.org/CVERecord?id=CVE-2026-43071 |