CVE Tools
Sign in

CVE-2025-39682

tls: fix handling of zero-length records on the rx_list

Published: Sep 5, 2025Updated: Sep 19, 2026 Sources: CVE List NVD BDU csafNVD-CWE-Other
9.8CRITICAL
NVD MITRE
EPSS Score
1.2%
Top 33.2%
CISA KEV
Active Exploitation
Since Sep 18, 2026
Exploits
1 Known
Remediation
Patch Available
Self-Check
OpenVAS

Description

SIMATIC CN 4100 contains multiple vulnerabilities which could potentially lead to a compromise in availability, integrity and confidentiality. Siemens has released a new version for SIMATIC CN 4100 and recommends to update to the latest version.

In plain language

AI Act now

This is a critical flaw in unpatched Linux kernel systems that attackers are already using, so small businesses running Linux servers should treat it as an emergency.

Executive summary

CVE-2025-39682 is a network-reachable Linux kernel TLS handling flaw involving zero-length records on the rx_list, with impacts to confidentiality, integrity, and availability.

If affected, business impact
Server takeoverSensitive data exposureData tamperingService outagesRansomware risk

What to do now

  1. Check every Linux server and appliance for its running kernel version and confirm with its operating-system vendor whether its installed security package includes CVE-2025-39682.
  2. Install the vendor-provided kernel security update; for the upstream 6.1 branch, update to 6.1.149 or later.
  3. Restart into the updated kernel and verify the running version after reboot.
  4. If an update cannot be applied immediately, follow your vendor's mitigation guidance and prioritize internet-facing systems.
Patch / advisory Usually a quick update

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

NVD-CWE-OtherCWE-754

Affected Products

Сообщество свободного программного обеспечения
oss-projectaka fsf
Debian GNU/LinuxOn-premOS
Operating Systems / linux-distro
LinuxOn-premOS
Operating Systems / linux-distro
ООО «Ред Софт»
commercial·RUaka red soft
РЕД ОСOn-premOS
Operating Systems / linux-distro
ООО «РусБИТех-Астра»
commercial·RUaka rusbitech-astra
Astra Linux Special EditionOn-premOS
Operating Systems / linux-distro
Red Hat Inc.
commercial·USaka red hat
Red Hat Enterprise LinuxOn-premOS
Operating Systems / linux-distro
Canonical Ltd.
commercial·GBaka canonical
UbuntuOn-premOS
Operating Systems / linux-distro
АО «ИВК»
commercial·RUaka ivk
АЛЬТ СП 10On-premOS
Operating Systems / linux-distro
and 4 more affected products View all →

Exploitability

CISA Known Exploited Vulnerability
Added to KEV:Sep 18, 2026
Remediation due:Sep 21, 2026

Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

1 exploit source identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available
Is your org exposed to CVE-2025-39682?Request an assessment to establish which checks are appropriate for your systems. Check my exposure

References

https://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f
git.kernel.org
https://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
git.kernel.org
https://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9
git.kernel.org
and 287 more references View all →
News mentions
1

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2025-39682 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows