CVE-2025-70100

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-06-03 · updated 2026-07-22
Weakness: CWE-369

Description

A divide-by-zero vulnerability in the ext4_block_set_lb_size function in src/ext4_blockdev.c of the lwext4 1.0.0 library allows attackers to cause a denial of service by providing a malformed ext4 filesystem image that results in a zero logical block size. The vulnerability is triggered during mount or image processing and leads to a Floating-Point Exception (FPE) under sanitizers or a runtime crash in standard builds due to missing validation of lb_size.

Affected products

Gkostka Lwext4: 1.0.0

References

https://github.com/gkostka/lwext4/issues/90
https://github.com/sigdevel/pocs/blob/main/res/lwext4/2/sig8_2_lwext4_ext4_blockdev_c_127
https://infosec.exchange/@sigdevel/116668952003072580
http://www.openwall.com/lists/oss-security/2026/06/29/5
https://github.com/gkostka/lwext4/issues/90

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