CVE-2025-70100

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.

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CVSS v3.1 Score

5.5

MEDIUM

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

EPSS — Exploit Prediction

0.0016

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-369 CWE-369

Affected Products

Vendor	Product	Versions
gkostka	lwext4	All

References

Advisories & Patches

https://github.com/gkostka/lwext4/issues/90 https://infosec.exchange/@sigdevel/116668952003072580 https://github.com/gkostka/lwext4/issues/90

Exploits

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 https://github.com/gkostka/lwext4/issues/90

Frequently Asked Questions

What is CVE-2025-70100? +

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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-70100? +

CVE-2025-70100 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0016, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2025-70100? +

CVE-2025-70100 affects products from gkostka, specifically: lwext4. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-70100? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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