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.
Remediation
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.
References
- Advisoryhttps://git.kernel.org/stable/c/2902c3ebcca52ca845c03182000e8d71d3a5196f
- Advisoryhttps://git.kernel.org/stable/c/c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677
- Advisoryhttps://git.kernel.org/stable/c/3439c15ae91a517cf3c650ea15a8987699416ad9
- Advisoryhttps://git.kernel.org/stable/c/29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
- Advisoryhttps://git.kernel.org/stable/c/62708b9452f8eb77513115b17c4f8d1a22ebf843
- Advisoryhttps://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- Advisoryhttps://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- Advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2025-39682
- Referencehttps://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- Referencehttps://cert-portal.siemens.com/productcert/html/ssa-032379.html
- Referencehttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-39682