CVE-2025-39682
Known exploited · CISA KEV
CVSS 7.1 HIGH: in the Linux kernel, the following vulnerability has been resolved: tls: fix handling of zero-length records on the… EPSS 1% (67th percentile).
CISA federal remediation date Sep 21
Vulnerabilities · 8h ago
CISA added three Linux kernel vulnerabilities to its Known Exploited Vulnerabilities list and told federal agencies to patch within three days. The flaws are tracked as CVE-2025-39682, CVE-2025-39964, and CVE-2026-53266.
The bugs hit different kernel paths: one mishandles zero-length records in the TLS receive path, one is a race in AF_ALG sockets when two writes collide, and one is an out-of-bounds write in bridge netfilter ebtables SNAT. In plain terms, the kernel can be pushed into reading, writing, or corrupting memory the wrong way, which can mean crashes, memory disclosure, or unauthorized modification.
For Linux hosts that carry containers, Kubernetes nodes, or shared workloads, the exposure sits below every app on the box. CISA’s three-day clock makes this a host update problem, not a service-by-service one, and any machine still on an affected kernel stays in scope until the kernel itself is fixed.
Known exploited · CISA KEV
CVSS 7.1 HIGH: in the Linux kernel, the following vulnerability has been resolved: tls: fix handling of zero-length records on the… EPSS 1% (67th percentile).
CISA federal remediation date Sep 21
Known exploited · CISA KEV
CVSS 3.3 LOW: in the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Disallow concurrent writes in… EPSS 0.8% (55th percentile).
CISA federal remediation date Sep 21
Known exploited · CISA KEV
CVSS 8.8 HIGH: in the Linux kernel, the following vulnerability has been resolved: netfilter: bridge: make ebt_snat ARP rewrite… EPSS 0.3% (20th percentile).
CISA federal remediation date Sep 21
3 sources covering this story
CISA alerts of active exploitation of three Linux kernel flaws
Cybersecurity and Infrastructure Security Agency (CISA) is warning that hackers are exploiting three Linux kernel vulnerabilities, one of them rated critical.
Organizations Warned of 3 Exploited Linux Kernel Vulnerabilities
Attackers could exploit the flaws to cause denial-of-service conditions, disclose memory, or modify memory.
Public Exploits Released for Four Linux Kernel Flaws That Enable Local Root
Public exploits for four patched Linux kernel flaws let local users gain root; three require unprivileged user namespaces.
Part of the PlainSec briefing for 2026-09-21