{"id":"CVE-2026-43265","summary":"KVM: x86: Ignore -EBUSY when checking nested events from vcpu_block()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: Ignore -EBUSY when checking nested events from vcpu_block()\n\nIgnore -EBUSY when checking nested events after exiting a blocking state\nwhile L2 is active, as exiting to userspace will generate a spurious\nuserspace exit, usually with KVM_EXIT_UNKNOWN, and likely lead to the VM's\ndemise.  Continuing with the wakeup isn't perfect either, as *something*\nhas gone sideways if a vCPU is awakened in L2 with an injected event (or\nworse, a nested run pending), but continuing on gives the VM a decent\nchance of surviving without any major side effects.\n\nAs explained in the Fixes commits, it _should_ be impossible for a vCPU to\nbe put into a blocking state with an already-injected event (exception,\nIRQ, or NMI).  Unfortunately, userspace can stuff MP_STATE and/or injected\nevents, and thus put the vCPU into what should be an impossible state.\n\nDon't bother trying to preserve the WARN, e.g. with an anti-syzkaller\nKconfig, as WARNs can (hopefully) be added in paths where _KVM_ would be\nviolating x86 architecture, e.g. by WARNing if KVM attempts to inject an\nexception or interrupt while the vCPU isn't running.","modified":"2026-05-18T06:00:14.557753223Z","published":"2026-05-06T11:28:51.552Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43265.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1c957773063ed3264953597e32990a748381caf6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1e88b5f854bdb469424132e0bb44793ad7a7c20a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2657439265d34a911886b916ba8be97ecc117d51"},{"type":"WEB","url":"https://git.kernel.org/stable/c/78265cd066d73a5cb41c088fcae4a2515e480d97"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ead63640d4e72e6f6d464f4e31f7fecb79af8869"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ec3be7dc9391085a2d96700e159d66d1328b7ff6"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43265.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-43265"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"26844fee6adee9b1557d2279b0506285de9ee82b"},{"fixed":"78265cd066d73a5cb41c088fcae4a2515e480d97"},{"fixed":"ec3be7dc9391085a2d96700e159d66d1328b7ff6"},{"fixed":"2657439265d34a911886b916ba8be97ecc117d51"},{"fixed":"1e88b5f854bdb469424132e0bb44793ad7a7c20a"},{"fixed":"1c957773063ed3264953597e32990a748381caf6"},{"fixed":"ead63640d4e72e6f6d464f4e31f7fecb79af8869"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-43265.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.1.0"},{"fixed":"6.1.167"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.130"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.77"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.17"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"6.19.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-43265.json"}}],"schema_version":"1.7.5"}