What is CVE-2021-45257?

CVE-2021-45257 is a medium-severity vulnerability in Nasm Netwide Assembler, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.5/10. Published 2021-12-22.

How severe is CVE-2021-45257?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Vulnerability in Nasm Netwide Assembler

CVE-2021-45257

An infinite loop vulnerability exists in nasm 2.16rc0 via the gpaste_tokens function.

Published 2021-12-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.007 (50.0th percentile), scored 2026-10-01.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Nasm Netwide Assembler — versions 2.16

Weakness classification (CWE)

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

References

bugzilla.nasm.us/show_bug.cgi (Issue Tracking, Broken Link)

Frequently asked questions

What is CVE-2021-45257?: CVE-2021-45257 is a medium-severity vulnerability in Nasm Netwide Assembler, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.5/10. Published 2021-12-22.
How severe is CVE-2021-45257?: Medium severity. CVSS v3 base score is 5.5 out of 10.