{"id":"CVE-2026-43265","title":"KVM: x86: Ignore -EBUSY when checking nested events from vcpu_block()","summary":"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 e…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < 78265cd066d73a5cb41c088fcae4a2515e480d97","Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < ec3be7dc9391085a2d96700e159d66d1328b7ff6","Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < 2657439265d34a911886b916ba8be97ecc117d51","Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < 1e88b5f854bdb469424132e0bb44793ad7a7c20a","Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < 1c957773063ed3264953597e32990a748381caf6","Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < ead63640d4e72e6f6d464f4e31f7fecb79af8869","Linux 6.1"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T15:32:33.106636Z"},"published":"2026-05-06","updated":"2026-11-06","sourceUpdated":"2026-11-06T15:42:45.276Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43265","references":[{"url":"https://git.kernel.org/stable/c/78265cd066d73a5cb41c088fcae4a2515e480d97"},{"url":"https://git.kernel.org/stable/c/ec3be7dc9391085a2d96700e159d66d1328b7ff6"},{"url":"https://git.kernel.org/stable/c/2657439265d34a911886b916ba8be97ecc117d51"},{"url":"https://git.kernel.org/stable/c/1e88b5f854bdb469424132e0bb44793ad7a7c20a"},{"url":"https://git.kernel.org/stable/c/1c957773063ed3264953597e32990a748381caf6"},{"url":"https://git.kernel.org/stable/c/ead63640d4e72e6f6d464f4e31f7fecb79af8869"}],"tags":["cve.org"],"epss":0.00119,"epssPercentile":0.0178,"ingestedAt":"2026-11-06T15:54:03.957Z","slug":"CVE-2026-43265","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < 78265cd066d73a5cb41c088fcae4a2515e480d97`\n- `Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < ec3be7dc9391085a2d96700e159d66d1328b7ff6`\n- `Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < 2657439265d34a911886b916ba8be97ecc117d51`\n- `Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < 1e88b5f854bdb469424132e0bb44793ad7a7c20a`\n- `Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < 1c957773063ed3264953597e32990a748381caf6`\n- `Linux >= 26844fee6adee9b1557d2279b0506285de9ee82b < ead63640d4e72e6f6d464f4e31f7fecb79af8869`\n- `Linux 6.1`\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":[]}