From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E343320459A for ; Wed, 1 Apr 2026 08:37:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775032676; cv=none; b=lsKUyWpli5ak/6v8rga1RaGwcuiXPTj3xEAdrQTqGzr/Hyn7ESZW8gZM0/lndila/3+qXfKbOT4hQveF7/RN5BNsm3zd6Je370rHsWUe5Ape2+2GPfyXB2XoqLBjkDAvtLVhavCjmNE6atvDhoBI4LUMIq1J2JdbFv3lk48KBuQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775032676; c=relaxed/simple; bh=q1YQmZUgoRqaD9A/dHYV4LVh0zIHFWJBn+9QwjkJAb0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=X6+oYkWE2GhfZdOm2p3pOXNx8lS5LsNoNYuFod6E4JMLAZrBkfSttTn4s2CrxSweRlHE8qDkHu/zz3Vv3L/0ZsRDWkfKsCkoghzR3W8qWXWBehuTn2xg3LR7IV/zIMxkTYs6xn44yN2S0Xonimet1VKAjNADObFni2Vmqe3lqVs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xx+NuhM9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xx+NuhM9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E952C4CEF7; Wed, 1 Apr 2026 08:37:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775032675; bh=q1YQmZUgoRqaD9A/dHYV4LVh0zIHFWJBn+9QwjkJAb0=; h=From:To:Cc:Subject:Date:Reply-To:From; b=xx+NuhM9vlOF9oCJVPmRMNK+1BCimeKnsb8sBb1Vi3r2e50oSP62Sl+gEx8TS3Qa7 pCOZXBhxGC3rqeiPifH4egR7vWy2G1sZrN2jgQCxVOfGgb+6M7Uk3NitzK4zQFOzpP LZ7vHosiA5OP7CMUO7DBD4txUoubr7+MQHwxXqiY= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-23402: KVM: x86/mmu: Only WARN in direct MMUs when overwriting shadow-present SPTE Date: Wed, 1 Apr 2026 10:37:10 +0200 Message-ID: <2026040110-CVE-2026-23402-c852@gregkh> X-Mailer: git-send-email 2.53.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2870; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=qK4ySpFEvi5SAO9PO8/gSMwoRVGkWQeUoyq+aYKmvLo=; b=owGbwMvMwCRo6H6F97bub03G02pJDJlnbppz/r2r7dGRGJv2/tDOe7y/r/YeDwmrf7g0Qurds hXzL0xf3hHLwiDIxCArpsjyZRvP0f0VhxS9DG1Pw8xhZQIZwsDFKQATsZNlmJ+TaMaRVMW1L9fH aUfw0zlH4wuajBnmB18Wbv12+4h/THb+prZkmUdB76evBQA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Only WARN in direct MMUs when overwriting shadow-present SPTE Adjust KVM's sanity check against overwriting a shadow-present SPTE with a another SPTE with a different target PFN to only apply to direct MMUs, i.e. only to MMUs without shadowed gPTEs. While it's impossible for KVM to overwrite a shadow-present SPTE in response to a guest write, writes from outside the scope of KVM, e.g. from host userspace, aren't detected by KVM's write tracking and so can break KVM's shadow paging rules. ------------[ cut here ]------------ pfn != spte_to_pfn(*sptep) WARNING: arch/x86/kvm/mmu/mmu.c:3069 at mmu_set_spte+0x1e4/0x440 [kvm], CPU#0: vmx_ept_stale_r/872 Modules linked in: kvm_intel kvm irqbypass CPU: 0 UID: 1000 PID: 872 Comm: vmx_ept_stale_r Not tainted 7.0.0-rc2-eafebd2d2ab0-sink-vm #319 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:mmu_set_spte+0x1e4/0x440 [kvm] Call Trace: ept_page_fault+0x535/0x7f0 [kvm] kvm_mmu_do_page_fault+0xee/0x1f0 [kvm] kvm_mmu_page_fault+0x8d/0x620 [kvm] vmx_handle_exit+0x18c/0x5a0 [kvm_intel] kvm_arch_vcpu_ioctl_run+0xc55/0x1c20 [kvm] kvm_vcpu_ioctl+0x2d5/0x980 [kvm] __x64_sys_ioctl+0x8a/0xd0 do_syscall_64+0xb5/0x730 entry_SYSCALL_64_after_hwframe+0x4b/0x53 ---[ end trace 0000000000000000 ]--- The Linux kernel CVE team has assigned CVE-2026-23402 to this issue. Affected and fixed versions =========================== Issue introduced in 6.16 with commit 11d45175111d933c5175acc28e56af2213dd5cd6 and fixed in 7.0-rc6 with commit df83746075778958954aa0460cca55f4b3fc9c02 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-23402 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: arch/x86/kvm/mmu/mmu.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/df83746075778958954aa0460cca55f4b3fc9c02