CVE-2025-39756

Local service interruption via oversized descriptor tables

Published Sep 11, 2025 · Updated Sep 8, 2026

Resource exhaustion in Linux kernel file-descriptor tables allows local users to interrupt service through a high-numbered dup2 call. alloc_fdtable multiplies the requested descriptor count into pointer-array and bitmap sizes, then passes values above INT_MAX to kvmalloc without an earlier bound. The path requires an unusually high nr_open and process limit; it produces an impractical allocation attempt, allocation failure, and a kernel warning.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Linux kernel file-descriptor tables allows local users to interrupt service through a high-numbered dup2 call. alloc_fdtable multiplies the requested descriptor count into pointer-array and bitmap sizes, then passes values above INT_MAX to kvmalloc without an earlier bound. The path requires an unusually high nr_open and process limit; it produces an impractical allocation attempt, allocation failure, and a kernel warning.

The record

CVE
CVE-2025-39756
Published
Sep 11, 2025
Updated
Sep 8, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-401, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 11, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=V3.1.5 <*
  2. Affected versionversion=V3.1.6 <*

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*; version=V3.1.6 <*
The Linux Kernel Organization · Linuxversion=2.6.25; version=9cfe015aa424b3c003baba3841a60dd9b5ad319b <04a2c4b4511d186b0fce685da21085a5d4acd370; version=9cfe015aa424b3c003baba3841a60dd9b5ad319b <237e416eb62101f21b28c9e6e564d10efe1ecc6f; version=9cfe015aa424b3c003baba3841a60dd9b5ad319b <628fc28f42d979f36dbf75a6129ac7730e30c04e; version=9cfe015aa424b3c003baba3841a60dd9b5ad319b <749528086620f8012b83ae032a80f6ffa80c45cd; version=9cfe015aa424b3c003baba3841a60dd9b5ad319b <9f61fa6a2a89a610120bc4e5d24379c667314b5c; version=9cfe015aa424b3c003baba3841a60dd9b5ad319b <b4159c5a90c03f8acd3de345a7f5fc63b0909818; version=9cfe015aa424b3c003baba3841a60dd9b5ad319b <d4f9351243c17865a8cdbe6b3ccd09d0b13a7bcc; version=9cfe015aa424b3c003baba3841a60dd9b5ad319b <dfd1f4ea98c3bd3a03d12169b5b2daa1f0a3e4ae; version=9cfe015aa424b3c003baba3841a60dd9b5ad319b <f95638a8f22eba307dceddf5aef9ae2326bbcf98
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.5 <*; version=V3.1.6 <*
Siemens · SIMATIC CN 4100version=0 <V5.0
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*; version=V3.1.6 <*

Published CVSS scores

5.5Siemens ProductCERTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5OracleCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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