CVE-2020-21685

Publication date 22 August 2023

Last updated 16 September 2025

Ubuntu priority

Cvss 3 Severity Score

Description

Buffer Overflow vulnerability in hash_findi function in hashtbl.c in nasm 2.15rc0 allows remote attackers to cause a denial of service via crafted asm file.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
nasm	25.04 plucky	Not affected
	24.10 oracular	Ignored end of life, was needs-triage
	24.04 LTS noble	Not affected
	23.10 mantic	Ignored end of life, was needs-triage
	23.04 lunar	Ignored end of life, was needs-triage
	22.04 LTS jammy	Not affected
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Ignored end of standard support

Notes

octagalland

Upstream closed the issue after failing to reproduce it with the provided POC. We can't reproduce either.

Severity score breakdown

CVSS version: CVSS v3.0

Base score 5.5 · Medium

Base metrics

Parameter	Value
Attack vector	Local
Attack complexity	Low
Privileges required	None
User interaction	Required
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	High

Scores

Parameter	Value
Base score	5.5 · Medium
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H