Threat Scope & Field Impact:
Cybersecurity threat intelligence monitors have confirmed active in-the-wild exploitation of CVE-2025-39682 targeting Linux Kernel. Successful exploitation allows threat actors to compromise application integrity and threaten user data confidentiality.
Technical Advisory Summary: 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.
CISA KEV Catalog: Officially cataloged by CISA as actively weaponized against production targets.
Recommended Mitigation & Action:
- Required Vendor 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.
- Remediation Timeline: Apply security patches immediately (Federal Remediation Due Date: 2026-09-21).
- Defensive Telemetry: We advise journalists, frontline defenders, and civil society organizations utilizing this platform to inspect updates and isolate unpatched endpoints.