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critical9.8Known exploited

CVE-2025-39682

Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability

Exploited in the wild

This vulnerability is on the CISA Known Exploited Vulnerabilities list, added 2026-09-18. Federal due date: 2026-09-21.

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.

Impact

Linux Kernel contains an improper check for unusual or exceptional conditions vulnerability in the TLS receive path which allows a zero-length record retrieved from the rx_list to bypass the intended recvmsg() record-type handling, potentially causing subsequent TLS records to be processed using incorrect zero-copy and queuing assumptions. The impacted product(s) could be end-of-life (EoL) and/or end-of-service (EoS). Users are advised to discontinue use and/or transition to a supported version.

Affected products

VendorProductAffected versions
LinuxLinux Kernel
from 6.0 before 6.1.149
from 6.2 before 6.6.103
from 6.7 before 6.12.44
from 6.13 before 6.16.4
Version 6.17
DebianDebian Linux
Version 11.0
SiemensSimatic Cn 4100 Firmware
before 5.0

Weakness classification

CWE-754

References