{"cve":"CVE-2026-89923","nvd":{"published":"2026-09-16T11:17:01.397","modified":"2026-10-19T09:18:37.817","status":"Received","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.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/053f2068cf9b0654b651fed5ad7649d3deb982bf","https://git.kernel.org/stable/c/544a5a665019cef394ce8bda97fa7a2cab253781","https://git.kernel.org/stable/c/6c996b12bbe4a6023076e8eee3cfaf2cc99db76c","https://git.kernel.org/stable/c/9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63","https://git.kernel.org/stable/c/b5acacfdb8966abff91836c1c5bd7da59d8a526e"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:54:41.405518556+00:00"},"epss":{"cve":"CVE-2026-89923","score":0.00211,"percentile":0.11181,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}