What is CVE-2026-2739?

CVE-2026-2739 is a medium-severity vulnerability in Bn.js, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.3/10. Published 2026-02-20.

How severe is CVE-2026-2739?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Bn.js

CVE-2026-2739

This affects versions of the package bn.js before 5.2.3. Calling maskn(0) on any BN instance corrupts the internal state, causing toString(), divmod(), and other methods to enter an infinite loop, hanging the process indefinitely.

Published 2026-02-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

EPSS exploit prediction

EPSS: 0.006 (46.7th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 46.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001

Affected products

Bn.js — versions 0

Weakness classification (CWE)

CWE-835 — Loop with Unreachable Exit Condition (Infinite Loop)

References

Frequently asked questions

What is CVE-2026-2739?: CVE-2026-2739 is a medium-severity vulnerability in Bn.js, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.3/10. Published 2026-02-20.
How severe is CVE-2026-2739?: Medium severity. CVSS v3 base score is 5.3 out of 10.