An issue was discovered in NASM version 2.16rc0.

published 2022-07-26 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-20154

cvss: 5.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits: 0; none known

An issue was discovered in NASM version 2.16rc0. There are memory leaks in nasm_calloc() in nasmlib/alloc.c.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-33450 updated 2026-11-07 cvss 5.5

nasm: memory leak in nasm_calloc() in nasmlib/alloc.c

Red Hat Enterprise Linux 6 nasm, nasm-rdoff Red Hat Enterprise Linux 7 nasm, nasm-rdoff
affected: no fix planned “Out of support scope”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

bugzilla.nasm.us https://bugzilla.nasm.us/show_bug.cgi?id=3392758 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Classification

Weakness

CWE-401 Missing Release of Memory after Effective Lifetime

References

bugzilla.nasm.us /show_bug.cgi?id=3392758
exploit, issue-tracking, third-party-advisory
gist.github.com /Clingto/bb632c0c463f4b2c97e4f65f751c5e6d
third-party-advisory

Sources

CVE List CVE-2021-33450
NVD CVE-2021-33450

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary