A divide-by-zero vulnerability in the ext4_block_set_lb_size function in…
Key facts
- Attack vector
- Local
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-369.
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2025-70100
- 2026-10-03 Alias added: GHSA-43cg-f93f-9jhx
References
More Gkostka Lwext4 vulnerabilities
- TI-2025-43032 An out-of-bounds read in the ext4_ext_binsearch_idx function in src/ext4_extent.c of the… CVSS 3.1MEDIUM 6.5
Sources
- CVE-2025-70100 · CVE Program
- CVE-2025-70100 · NVD
- FIRST EPSS
- GHSA-43cg-f93f-9jhx · GitHub Advisory Database · CC BY 4.0
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