{"id":"CVE-2025-39703","title":"kernel: net, hsr: reject HSR frame if skb can't hold tag (CVE-2025-39703)","summary":"A flaw was found in the Linux kernel's High-availability Seamless Redundancy (HSR) networking subsystem. This flaw allows an adjacent network attacker or a local user to cause a denial of service (DoS) by transmitting malformed HSR network…","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":"CWE-1286","vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","affected":["enterprise_linux 10","enterprise_linux 9"],"published":"2025-09-05","updated":"2026-10-16","sourceUpdated":"2026-10-16T22:56:06+00:00","source":"CSAF","sourceUrl":"https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39703.json","references":[{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39703.json"},{"url":"https://access.redhat.com/security/cve/CVE-2025-39703"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2393535"},{"url":"https://www.cve.org/CVERecord?id=CVE-2025-39703"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-39703"},{"url":"https://lore.kernel.org/linux-cve-announce/2025090549-CVE-2025-39703-b03b@gregkh/T"},{"url":"https://git.kernel.org/stable/c/8d9bc4a375a1ba05f7dfa0407de8e510ab9bd14d"},{"url":"https://git.kernel.org/stable/c/3ae272ab523dd6bdc26e879027ed79feac9dd1b3"},{"url":"https://git.kernel.org/stable/c/b640188b8a6690e685939053c7efdbc7818b5f4e"},{"url":"https://git.kernel.org/stable/c/b117c41b00902c1a7e24347c405cb82504aeae0b"},{"url":"https://git.kernel.org/stable/c/acd69b597bd3f76d3b3d322b84082226c00eeaa4"},{"url":"https://git.kernel.org/stable/c/61009439e4bd8d74e705ee15940760321be91d8a"},{"url":"https://git.kernel.org/stable/c/7af76e9d18a9fd6f8611b3313c86c190f9b6a5a7"}],"tags":["csaf","vex","red-hat","cve.org","score-dispute"],"epss":0.00376,"epssPercentile":0.31354,"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-15T21:53:38.514386Z"},"scores":{"vendor":6.5,"cna":9.8},"ingestedAt":"2026-10-15T22:48:25.521Z","slug":"CVE-2025-39703","body":"## Overview\n\nA flaw was found in the Linux kernel's High-availability Seamless Redundancy (HSR) networking subsystem. This flaw allows an adjacent network attacker or a local user to cause a denial of service (DoS) by transmitting malformed HSR network frames with incomplete tags. Due to insufficient packet length validation, processing these frames corrupts internal buffer state, triggering a kernel panic and crashing the system.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39703.json)\n\n**kernel: net, hsr: reject HSR frame if skb can't hold tag** — rated Moderate by Red Hat. Released 2025-09-05, updated 2026-10-16.\n\nAffected:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 9\n\nNo fix planned:\n\n- Red Hat Enterprise Linux 10\n- Red Hat Enterprise Linux 9\n\nNot affected:\n\n- Red Hat Enterprise Linux 6\n- Red Hat Enterprise Linux 7\n- Red Hat Enterprise Linux 8\n\n## Remediation\n\nFix deferred\n\nWorkarounds / mitigations:\n\n- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":223723,"id":"CVE-2025-39703","ts":1792238376787,"field":"cvss","old":"9.8","new":"6.5"},{"seq":223722,"id":"CVE-2025-39703","ts":1792238376787,"field":"severity","old":"critical","new":"medium"}]}