Out-of-bounds Read in Gkostka Lwext4
CVE-2025-70101
An out-of-bounds read in the ext4_ext_binsearch_idx function in src/ext4_extent.c of the lwext4 1.0.0 library allows attackers to cause a denial of service by supplying a specially crafted ext4 filesystem image. The vulnerability occurs due to insufficient validation of extent header fields before performing a binary search over extent index entries, which can result in invalid pointer calculations and an out-of-bounds memory read during extent tree traversal.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.003 (19.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 20th percentile — 19.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Gkostka Lwext4 — versions 1.0.0
Weakness classification (CWE)
References
- github.com/gkostka/lwext4/issues/91 (Exploit, Patch, Issue Tracking)
- github.com/sigdevel/pocs/blob/main/res/lwext4/3/sig11_lwext4_ext4_extent_815 (Exploit)
- infosec.exchange/@sigdevel/116668958927817708 (Exploit, Patch, Third Party Advisory)
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-70101?
- CVE-2025-70101 is a medium-severity vulnerability in Gkostka Lwext4, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2026-06-03.
- How severe is CVE-2025-70101?
- Medium severity. CVSS v3 base score is 6.5 out of 10.