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.
CVE-2025-70100
Score 5.5 from GitHub Security Advisory published 2026-06-03. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 5.5; sources differ by 0.0.
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.5
- EG Score
- 5.5(medium)
- EG Risk
- 41(Track)EG Risk 41/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity55% × 45%Exploitation40% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS
- 5.1%
- KEV
- Not listed
Published
June 3, 2026
Last Modified
July 22, 2026
Advisory Details (3)
Auto-updated Jun 16, 2026[security] lwext4/src/ext4_blockdev.c FPE in ext4_block_set_lb_size · Issue #90 · gkostka/lwext4 · GitHub
https://github.com/gkostka/lwext4/issues/90sigdevel: "Security Advisory: CVE-2025-70100 - Divide By Zer…" - Infosec Exchange
https://infosec.exchange/@sigdevel/116668952003072580pocs/res/lwext4/2/sig8_2_lwext4_ext4_blockdev_c_127 at main · sigdevel/pocs · GitHub
https://github.com/sigdevel/pocs/blob/main/res/lwext4/2/sig8_2_lwext4_ext4_blockdev_c_127Vendor Advisories for CVE-2025-70100(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 10× in last 7d / 56× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
Showing the most recent 100 of 102 total refreshes for this CVE.
- 2026-07-23 14:18 UTCEPSS rescore
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Frequently asked(5)
What is CVE-2025-70100?
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Dependency Blast Radius
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