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Vulnerability · Published Nov 12, 2025 · Assigned by Linux

CVE-2025-40119ext4: fix potential null deref in ext4_mb_init()

Unrated

In plain English

A security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS )–Not rated
Exploit odds (30 days)0.2%top 88.4% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix potential null deref in ext4_mb_init() In ext4_mb_init(), ext4_mb_avg_fragment_size_destroy() may be called when sbi->s_mb_avg_fragment_size remains uninitialized (e.g., if groupinfo slab cache allocation fails). Since ext4_mb_avg_fragment_size_destroy() lacks null pointer checking, this leads to a null pointer dereference. ================================================================== EXT4-fs: no memory for groupinfo slab cache BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD 0 P4D 0 Oops: Oops: 0002 [#1] SMP PTI CPU:2 UID: 0 PID: 87 Comm:mount Not tainted 6.17.0-rc2 #1134 PREEMPT(none) RIP: 0010:_raw_spin_lock_irqsave+0x1b/0x40 Call Trace: <TASK> xa_destroy+0x61/0x130 ext4_mb_init+0x483/0x540 __ext4_fill_super+0x116d/0x17b0 ext4_fill_super+0xd3/0x280 get_tree_bdev_flags+0x132/0x1d0 vfs_get_tree+0x29/0xd0 do_new_mount+0x197/0x300 __x64_sys_mount+0x116/0x150 do_syscall_64+0x50/0x1c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e ================================================================== Therefore, add necessary null check to ext4_mb_avg_fragment_size_destroy() to prevent this issue. The same fix is also applied to ext4_mb_largest_free_orders_destroy().

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Ubuntu:25.10linux6.17.0-14.14UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2025-40119
Ubuntu:25.10linux-aws6.17.0-1007.7UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-aws-6.176.17.0-1007.7~24.04.1UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2025-40119
Ubuntu:25.10linux-azure6.17.0-1008.8UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2025-40119
Ubuntu:25.10linux-azure-fdeno fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2025-40119
Ubuntu:25.10linux-gcp6.17.0-1007.7UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1008.8~24.04.1UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-nvidia-6.176.17.0-1008.8UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1011.11UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2025-40119
Ubuntu:25.10linux-oracle6.17.0-1007.7UBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1007.7~24.04.1UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2025-40119
Ubuntu:25.10linux-raspi6.17.0-1008.8UBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-40119
Ubuntu:25.10linux-realtime6.17.0-1006.7UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-40119
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-40119
Ubuntu:25.10linux-riscv6.17.0-14.14.1UBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2025-40119
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2025-40119

Affected products (as reported)

VendorProductVersions
Linux Linux d99d714f714c9492dc64d8ab4329b083dbfa9cab – before 08d9175578d6a8e9b81921898fbf01aa669cd2bef7eaacbb4e54f8a6c6674c16eff54f703ea63d5e – before 00110f3cfc9b34b2dfee2a6c9e55a0ae6df125aef7eaacbb4e54f8a6c6674c16eff54f703ea63d5e – before 3c3fac6bc0a9c00dbe65d8dc0d3a282afe4d3188
Linux Linux 6.17

References