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CVE-2025-39682

Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability

Linux KernelOperating systems
Open in ThreatlineRecord JSON
CVSS
9.8Critical
ExploitationExploited in the wildAdded to KEV 18 Sep 2026CISA KEV
Exploit odds (EPSS)2.88%Chance of exploitation activity in the next 30 days, higher than 86% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in2902c3ebcca52ca845c03182000e8d71d3a5196fAlso 3439c15ae91a517cf3c650ea15a8987699416ad9, 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e and 1 moreCVE List
Federal deadline21 Sep 2026Remediation due date for US federal agenciesCISA KEV
CISA required actionApply 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. CISA KEV
Patching is not enoughCISA requires federal agencies to look for signs of compromise on affected systems, not only patch (forensic triage under BOD 26-04). Treat exposed systems as possibly compromised. CISA guidance

What fixes it

  • 2902c3ebcca52ca845c03182000e8d71d3a5196fLinuxCVE List
  • 3439c15ae91a517cf3c650ea15a8987699416ad9LinuxCVE List
  • 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42eLinuxCVE List
  • 62708b9452f8eb77513115b17c4f8d1a22ebf843LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Timeline

  1. 5 Sep 2025, 17:20 UTCPublishedCVE List
  2. 18 Sep 2026Added to CISA KEVCISA KEV

Description

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.

Text from CVE List

Affected versions 12

  • Linuxaffected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 before 2902c3ebcca52ca845c03182000e8d71d3a5196fCVE List
  • Linuxaffected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 before c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677CVE List
  • Linuxaffected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 before 3439c15ae91a517cf3c650ea15a8987699416ad9CVE List
  • Linuxaffected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 before 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42eCVE List
  • Linuxaffected: 84c61fe1a75b4255df1e1e7c054c9e6d048da417 before 62708b9452f8eb77513115b17c4f8d1a22ebf843CVE List
  • Linuxaffected: 6.0CVE List
  • Linuxunaffected: all versions before 6.0CVE List
  • Linuxunaffected: 6.1.149 through 6.1.*CVE List
  • Linuxunaffected: 6.6.103 through 6.6.*CVE List
  • Linuxunaffected: 6.12.44 through 6.12.*CVE List
  • Linuxunaffected: 6.16.4 through 6.16.*CVE List
  • Linuxunaffected: 6.17CVE List

References 9