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CVE-2026-7007— Division by zero in Zephyr ext2 superblock parsing allows DoS via crafted filesystem image

Quick assessment

Affected
zephyrproject zephyr
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

zephyrproject zephyr是zephyrproject组织开源的一款实时操作系统内核。 zephyrproject zephyr 3.5.0版本至4.5.0之前版本存在数字错误漏洞，该漏洞源于Zephyr ext2文件系统在校验超级块时未验证s_blocks_per_group和s_inodes_per_group字段是否为零，在挂载过程中用作除数时导致整数除零，可能造成拒绝服务。

CVSS 4.6 · Medium EPSS 0.24% · P14

Affected Version Matrix 1

VendorProduct Version RangeStatus
zephyrproject zephyr 3.5.0< 4.4.2 affected
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I. Basic Information for CVE-2026-7007

Vulnerability Information
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Vulnerability Title
Division by zero in Zephyr ext2 superblock parsing allows DoS via crafted filesystem image
Source: CVE Program / CVE List V5
Vulnerability Description
The Zephyr ext2 file system validates the on-disk superblock in ext2_verify_disk_superblock() (subsys/fs/ext2/ext2_impl.c) before completing a mount. The validator checked the magic number, block size, revision and feature flags, but did not verify that the on-disk fields s_blocks_per_group and s_inodes_per_group are non-zero. Both fields are read directly from the image and are later used as divisors during mount-time initialization. During mount, get_ngroups() divides and modulos s_blocks_count by s_blocks_per_group (reached via ext2_fetch_block_group() from ext2_init_fs()), and get_itable_entry() divides (ino - 1) by s_inodes_per_group when fetching the root inode (both in subsys/fs/ext2/ext2_diskops.c). A superblock with either field set to zero therefore causes an integer division by zero during the mount sequence. An attacker who can present a crafted ext2 image to a device that mounts ext2 — removable media such as an SD card or a USB mass-storage device — can trigger this. On ARMv7-M / ARMv8-M-mainline Cortex-M targets, divide-by-zero trapping is enabled (SCB_CCR_DIV_0_TRP), so the division raises a UsageFault that Zephyr treats as a fatal error, producing a denial of service. The impact is limited to availability; the malformed value is consumed only as a divisor. The fix rejects a zero s_blocks_per_group or s_inodes_per_group in the superblock validator, returning -EINVAL so the mount fails before any block-group or inode I/O occurs.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
除零错误
Source: CVE Program / CVE List V5
Vulnerability Title
zephyrproject zephyr 数字错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
zephyrproject zephyr是zephyrproject组织开源的一款实时操作系统内核。 zephyrproject zephyr 3.5.0版本至4.5.0之前版本存在数字错误漏洞，该漏洞源于Zephyr ext2文件系统在校验超级块时未验证s_blocks_per_group和s_inodes_per_group字段是否为零，在挂载过程中用作除数时导致整数除零，可能造成拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
zephyrproject zephyr 3.5.0 ~ 4.4.2 -

II. Public POCs for CVE-2026-7007

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III. Intelligence Information for CVE-2026-7007

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Patches & Fixes for CVE-2026-7007 (1)

Vendor Advisories for CVE-2026-7007 (1)

IV. Related Vulnerabilities

Same product: zephyr
Same vendor: zephyrproject
Same weakness: CWE-369

V. Comments for CVE-2026-7007

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