What is CVE-2020-24978?

CVE-2020-24978 is a critical-severity vulnerability in Nasm Netwide Assembler, classified under Double Free. CVSS score: 9.8/10. Published 2020-09-04.

How severe is CVE-2020-24978?

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

Is CVE-2020-24978 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Double Free in Nasm Netwide Assembler

CVE-2020-24978

In NASM 2.15.04rc3, there is a double-free vulnerability in pp_tokline asm/preproc.c. This is fixed in commit 8806c3ca007b84accac21dd88b900fb03614ceb7.

Vulnerability class: Double Free

Published 2020-09-04 · 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: 0.014 (70.6th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 70.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000

Affected products

Nasm Netwide Assembler — versions 2.15.04

Weakness classification (CWE)

CWE-415 — Double Free

Public proof-of-concept exploits

References

bugzilla.nasm.us/show_bug.cgi (Exploit, Issue Tracking, Vendor Advisory)

Frequently asked questions

What is CVE-2020-24978?: CVE-2020-24978 is a critical-severity vulnerability in Nasm Netwide Assembler, classified under Double Free. CVSS score: 9.8/10. Published 2020-09-04.
How severe is CVE-2020-24978?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2020-24978 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.