{"id":"CVE-2026-89923","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: Free guest debug data on vcpu destroy\n\nkvm_s390_clear_bp_data() is only called from\nkvm_arch_vcpu_ioctl_set_guest_debug(), i.e","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: Free guest debug data on vcpu destroy\n\nkvm_s390_clear_bp_data() is only called from\nkvm_arch_vcpu_ioctl_set_guest_debug(), i.e. when user space changes or\ndi…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 27291e2165b6de70c476b7b675308113edd69a60 < 053f2068cf9b0654b651fed5ad7649d3deb982bf","Linux >= 27291e2165b6de70c476b7b675308113edd69a60 < 6c996b12bbe4a6023076e8eee3cfaf2cc99db76c","Linux >= 27291e2165b6de70c476b7b675308113edd69a60 < d6280fc540d8f4653c9b54a78cb747e128070f5e","Linux >= 27291e2165b6de70c476b7b675308113edd69a60 < 544a5a665019cef394ce8bda97fa7a2cab253781","Linux >= 27291e2165b6de70c476b7b675308113edd69a60 < 9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63","Linux >= 27291e2165b6de70c476b7b675308113edd69a60 < b5acacfdb8966abff91836c1c5bd7da59d8a526e","Linux >= 27291e2165b6de70c476b7b675308113edd69a60 < e4d8b7f176b976474e0800ba71ee2dfa3ce263c9","Linux >= 27291e2165b6de70c476b7b675308113edd69a60 < e7f698b09d4a7c36b299acf680fc50fe868e2bcd","Linux 3.16"],"published":"2026-09-16","updated":"2026-09-16","sourceUpdated":"2026-09-16T11:17:01.397","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-89923","references":[{"url":"https://git.kernel.org/stable/c/053f2068cf9b0654b651fed5ad7649d3deb982bf","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/544a5a665019cef394ce8bda97fa7a2cab253781","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6c996b12bbe4a6023076e8eee3cfaf2cc99db76c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b5acacfdb8966abff91836c1c5bd7da59d8a526e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d6280fc540d8f4653c9b54a78cb747e128070f5e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e4d8b7f176b976474e0800ba71ee2dfa3ce263c9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e7f698b09d4a7c36b299acf680fc50fe868e2bcd","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-16T10:53:53.971Z","epss":0.0021,"epssPercentile":0.11545,"slug":"CVE-2026-89923","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: Free guest debug data on vcpu destroy\n\nkvm_s390_clear_bp_data() is only called from\nkvm_arch_vcpu_ioctl_set_guest_debug(), i.e. when user space changes or\ndisables debugging. A vCPU that is destroyed while hardware breakpoints\nare still armed - the normal case when the VMM just exits or crashes -\nleaks hw_bp_info, hw_wp_info and all old_data buffers, since generic KVM\nfrees the vCPU right after kvm_arch_vcpu_destroy().\n\nThat is bounded by MAX_BP_COUNT entries, so roughly 8 KiB per vCPU, but\nit is unbounded over VM lifetimes. The allocations are\nGFP_KERNEL_ACCOUNT, so the charge also outlives the exiting process and\npins dying memcgs.\n\nFix by clearing the debug data on vCPU destruction. Calling it\nunconditionally is fine: struct kvm_vcpu is zero allocated, so for a vCPU\nthat never enabled debugging the counters are 0 and the pointers NULL.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}