CVE-2026-52969
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
A vulnerability was found in the Linux kernel's KVM subsystem in the kvm_reset_dirty_gfn() function. Missing overflow check when adding offset and mask allows bypassing range validation via integer wrap. An attacker can exploit this for out-of-bounds memory access.
Risk Assessment
The risk involves potential out-of-bounds memory operations by any process with /dev/kvm access, which could lead to privilege escalation or system integrity compromise.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit adding separate offset check before mask addition). Monitor official security advisories from your distribution.
Other vulnerabilities in Linux kernel
See all- CVE-2026-99284Unknown
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- CVE-2026-99283Unknown
A bug in the Linux kernel netfilter conntrack TCP timeout selection was found. When an RST packet does not exactly match the expected sequence number, the conntrack entry remains ESTABLISHED, but the short CLOSE timeout (10 seconds) is still applied. A second non-exact RST can lower the timeout before the challenge ACK rate limit expires, allowing the conntrack entry to expire while both TCP endpoints remain established.
- CVE-2026-99282Unknown
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- CVE-2026-99281Unknown
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- CVE-2026-99280Unknown
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- CVE-2026-99278Unknown
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- CVE-2026-99259Unknown
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- CVE-2026-99258Unknown
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- CVE-2026-99257Unknown
In the Linux kernel, the shared GPIO mechanism based on platform lookup tables requires an associated struct device. An fwnode-based lookup with no associated device currently causes a NULL-pointer dereference. The fix adds a check that lets the kernel gracefully handle this situation with an error.
- CVE-2026-99256Unknown
In the Linux kernel, the dm cache module used a rw_semaphore for background_work_lock, although write locks on rw_semaphores have strict owner semantics. The locking process was not always the same as the unlocking one, triggering a warning with CONFIG_DEBUG_RWSEMS during suspend/resume of a cache device. The fix replaces the rw_semaphore with a spinlock and a wait queue.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: KVM: Reject wrapped offset in kvm_reset_dirty_gfn() kvm_reset_dirty_gfn() guards the gfn range with if (!memslot || (offset + __fls(mask)) >= memslot->npages) return; but offset is u64 and the addition is unchecked. The check can be silently bypassed by a u64 wrap. The dirty ring backing those entries is MAP_SHARED at KVM_DIRTY_LOG_PAGE_OFFSET of the vcpu fd, so the VMM can rewrite the slot and offset fields of any entry between when the kernel pushes them and when KVM_RESET_DIRTY_RINGS consumes them. On reset, kvm_dirty_ring_reset() re-reads the values via READ_ONCE() and feeds them straight back into this check; only the flags handshake is treated as the handover, the slot/offset payload is taken on trust. Crafting two entries entry[i].offset = 0xffffffffffffffc1 entry[i+1].offset = 0 makes the coalescing loop in kvm_dirty_ring_reset() compute delta = (s64)(0 - 0xffffffffffffffc1) = 63 which falls in [0, BITS_PER_LONG), so it folds entry[i+1] into the existing mask by setting bit 63. The trailing kvm_reset_dirty_gfn() call then sees offset = 0xffffffffffffffc1 and __fls(mask) = 63; the sum is 0 in u64 and the bounds check passes. That offset propagates into kvm_arch_mmu_enable_log_dirty_pt_masked() unchanged. On the legacy MMU path -- kvm_memslots_have_rmaps() == true, i.e. shadow paging, any VM that has allocated shadow roots, or a write-tracked slot -- it reaches gfn_to_rmap(), which indexes slot->arch.rmap[0][] with a near-U64_MAX gfn. That is an out-of-bounds load of a kvm_rmap_head, followed by a conditional clear of PT_WRITABLE_MASK in whatever the loaded pointer points at. The path is reachable from any process holding /dev/kvm. Range-check offset on its own first, so the addition cannot wrap. memslot->npages is bounded well below U64_MAX, so once offset < npages holds, offset + __fls(mask) (with __fls(mask) < BITS_PER_LONG) stays in range.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS