{"id":"CVE-2026-89923","state":"PUBLISHED","title":"KVM: s390: Free guest debug data on vcpu destroy","description":"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\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.","publishedAt":"2026-09-16T10:32:16.765Z","updatedAt":"2026-10-19T08:54:58.219Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"053f2068cf9b0654b651fed5ad7649d3deb982bf","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"6c996b12bbe4a6023076e8eee3cfaf2cc99db76c","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"d6280fc540d8f4653c9b54a78cb747e128070f5e","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"544a5a665019cef394ce8bda97fa7a2cab253781","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"b5acacfdb8966abff91836c1c5bd7da59d8a526e","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"e4d8b7f176b976474e0800ba71ee2dfa3ce263c9","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"e7f698b09d4a7c36b299acf680fc50fe868e2bcd","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/s390/kvm/kvm-s390.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.16","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/s390/kvm/kvm-s390.c"]}],"references":["https://git.kernel.org/stable/c/053f2068cf9b0654b651fed5ad7649d3deb982bf","https://git.kernel.org/stable/c/6c996b12bbe4a6023076e8eee3cfaf2cc99db76c","https://git.kernel.org/stable/c/d6280fc540d8f4653c9b54a78cb747e128070f5e","https://git.kernel.org/stable/c/544a5a665019cef394ce8bda97fa7a2cab253781","https://git.kernel.org/stable/c/9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63","https://git.kernel.org/stable/c/b5acacfdb8966abff91836c1c5bd7da59d8a526e","https://git.kernel.org/stable/c/e4d8b7f176b976474e0800ba71ee2dfa3ce263c9","https://git.kernel.org/stable/c/e7f698b09d4a7c36b299acf680fc50fe868e2bcd"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89923.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89923","state":"PUBLISHED","datePublished":"2026-09-16T10:32:16.765Z","dateUpdated":"2026-10-19T08:54:58.219Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.775Z"},"containers":{"cna":{"title":"KVM: s390: Free guest debug data on vcpu destroy","descriptions":[{"lang":"en","value":"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\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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"053f2068cf9b0654b651fed5ad7649d3deb982bf","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"6c996b12bbe4a6023076e8eee3cfaf2cc99db76c","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"d6280fc540d8f4653c9b54a78cb747e128070f5e","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"544a5a665019cef394ce8bda97fa7a2cab253781","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"b5acacfdb8966abff91836c1c5bd7da59d8a526e","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"e4d8b7f176b976474e0800ba71ee2dfa3ce263c9","versionType":"git"},{"version":"27291e2165b6de70c476b7b675308113edd69a60","status":"affected","lessThan":"e7f698b09d4a7c36b299acf680fc50fe868e2bcd","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/s390/kvm/kvm-s390.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.16","versionType":"semver"},{"version":"5.10.270","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.221","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.188","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.157","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.110","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.5","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/s390/kvm/kvm-s390.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/053f2068cf9b0654b651fed5ad7649d3deb982bf"},{"url":"https://git.kernel.org/stable/c/6c996b12bbe4a6023076e8eee3cfaf2cc99db76c"},{"url":"https://git.kernel.org/stable/c/d6280fc540d8f4653c9b54a78cb747e128070f5e"},{"url":"https://git.kernel.org/stable/c/544a5a665019cef394ce8bda97fa7a2cab253781"},{"url":"https://git.kernel.org/stable/c/9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63"},{"url":"https://git.kernel.org/stable/c/b5acacfdb8966abff91836c1c5bd7da59d8a526e"},{"url":"https://git.kernel.org/stable/c/e4d8b7f176b976474e0800ba71ee2dfa3ce263c9"},{"url":"https://git.kernel.org/stable/c/e7f698b09d4a7c36b299acf680fc50fe868e2bcd"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:54:58.219Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"5.10.270"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"6.12.110"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"6.18.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"7.2.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}