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Fencer Intel
medium 5.5

CVE-2025-70100 json

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 t…

published 5mo ago modified 3mo ago also EUVD-2025-210054

cvss
5.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits
0
none known

Summary

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.

Patch / fix

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
5mo ago

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/gkostka/lwext4/issues/90 referenced PoC, tagged "exploit" by a source, unverified
  • infosec.exchange https://infosec.exchange/@sigdevel/116668952003072580 referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/sigdevel/pocs/blob/main/res/lwext4/2/sig8_2_lwext4_ext4_blockdev_c_127 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CNA 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.