CVE-2026-63955
In the Linux kernel, the following vulnerability has been resolved:
mm/vmalloc: do not trigger BUG() on BH disabled context
__get_vm_area_node() currently triggers a BUG() if in_interrupt() returns
true. However, in_interrupt() also reports true when BH are disabled.
The bridge code can call rhashtable_lookup_insert_fast() with bottom
halves disabled:
__vlan_add()
-> br_fdb_add_local()
spin_lock_bh(&br->hash_lock); <-- Disable BH
-> fdb_add_local()
-> fdb_create()
-> rhashtable_lookup_insert_fast()
-> kvmalloc()
-> vmalloc()
-> __get_vm_area_node()
-> BUG_ON(in_interrupt())
spin_unlock_bh(&br->hash_lock)
this triggers the BUG() despite the caller not being in NMI or
hard IRQ context.
Replace the in_interrupt() check with in_nmi() || in_hardirq().
CSIRTS triage
- What
- Multiple kernel vulnerabilities across architectures and driver subsystems including AMD processor microarchitectural flaws and cache isolation issues.
- Who is affected
- NVIDIA BaseOS systems running affected Linux kernel versions.
- Urgency
- Moderate; privilege escalation and DoS vectors present, primarily requiring local access.
- Action
- Apply USN-8664-1 kernel security update for NVIDIA BaseOS.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.49% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 40% of all EPSS-scored CVEs.
Advisory coverage (6)
- unknownUSN-8664-1: Linux kernel (NVIDIA BaseOS) vulnerabilitiesubuntu · 2026-08-20
- unknownUSN-8663-1: Linux kernel (NVIDIA) vulnerabilitiesubuntu · 2026-08-20
- highUSN-8618-1: Linux kernel vulnerabilitiesubuntu · 2026-07-28
- highUSN-8603-1: Linux kernel (Azure) vulnerabilitiesubuntu · 2026-07-24
- highUSN-8593-1: Linux kernel vulnerabilitiesubuntu · 2026-07-23
- highCVE-2026-63955: In the Linux kernel, the following vulnerability has been resolved: mm/vmalloc: do not trigger…nvd · 2026-07-19
External references
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