CVE-2020-21686 Use after free in n/a
Remote attackers can cause denial of service in NASM via crafted assembly files due to a stack-use-after-scope bug.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2020-21686?
CVE-2020-21686 is a medium-severity use after free vulnerability in Nasm Netwide Assembler, published on 22 Aug 2023. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
A stack-use-after-scope issue discovered in expand_mmac_params function in preproc.c in nasm before 2.15.04 allows remote attackers to cause a denial of service via crafted asm file.
Weakness: CWE-562
Which versions are affected by CVE-2020-21686?
It affects 1 product.
Products include Nasm Netwide Assembler.
How do I fix CVE-2020-21686?
Upgrade to a fixed version.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2020-21686 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-21686 exists.
Other vulnerabilities in Nasm Netwide Assembler
Sources
Also known as DEBIAN-CVE-2020-21686, GHSA-f5w2-2h32-hmg6, JLSEC-2026-201, UBUNTU-CVE-2020-21686.