Quick answers
- Is CVE-2025-70100 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2025-70100 being exploited in the wild.
- How severe is CVE-2025-70100?
- Informational severity, with a CVSS score of 5.5, published 3 June 2026.
- Which products and versions are affected?
- Grzegorz Kostka Lwext4 1.0.0.
- Is there a fix for CVE-2025-70100?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2025-70100 attacked?
- It is attacked with local access, in a software library.
- Am I affected by CVE-2025-70100?
- Check whether you run Grzegorz Kostka Lwext4 at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A divide-by-zero vulnerability exists in the ext4_block_set_lb_size function within src/ext4_blockdev.c of the lwext4 1.0.0 library. The root cause is a lack of validation for the logical block size (lb_size) parameter; when a crafted ext4 image with a zero logical block size is processed during an ext4_mount operation, the library performs arithmetic division by zero. This leads to a Floating-Point Exception (FPE) and a subsequent runtime crash. The attack requires the victim to attempt to mount or process a malicious filesystem image. As of the advisory date, the issue was reported via GitHub issues and demonstrated with a proof-of-concept (PoC) using AFL fuzzing.
Affected products
- gkostka lwext4 1.0.0
Timeline
- 2025-12-09: disclosed: Issue reported on GitHub repository
- 2026-06-03: advisory: CVE-2025-70100 published in NVD