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CVE-2026-63955

HIGHCVSS 7.5/10EPSS 0.47%

Last modified

CVE-2026-63955 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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().. EPSS estimates a 0.47% chance of exploitation in the next 30 days.

Description

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().

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
0.47%

37.9th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= c6307674ed82c0c57d6e1e3408e84ac449ab8e94, < ad7eff07b625f53c3fb513b30d7a8c5a79fbc7ce; >= c6307674ed82c0c57d6e1e3408e84ac449ab8e94, < 04aa71da5f35aacdc9ae9cb5150947daa624f641
LinuxLinux6.19

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is 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().
How severe is CVE-2026-63955?
CVE-2026-63955 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.47% probability of exploitation in the next 30 days.
How do I fix CVE-2026-63955?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST