What is CVE-2021-3751?

CVE-2021-3751 is a critical-severity vulnerability in Bfabiszewski Bfabiszewski/libmobi, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2021-09-15.

How severe is CVE-2021-3751?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Bfabiszewski Bfabiszewski/libmobi

CVE-2021-3751

libmobi is vulnerable to Out-of-bounds Write

Vulnerability class: Buffer Overflow

Published 2021-09-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.012 (67.9th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 68th percentile — 67.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: 0.000

Affected products

Bfabiszewski Bfabiszewski/libmobi — versions unspecified
Libmobi Project

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

huntr.dev/bounties/fcb4383c-bc27-4b89-bfce-6b041f0cb769 (Exploit, Patch, Third Party Advisory, Issue Tracking)
github.com/bfabiszewski/libmobi/commit/ab5bf0e37e540eac682a14e628853b918626e72b (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-3751?: CVE-2021-3751 is a critical-severity vulnerability in Bfabiszewski Bfabiszewski/libmobi, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2021-09-15.
How severe is CVE-2021-3751?: Critical severity. CVSS v3 base score is 9.8 out of 10.