Security readout for executives and security teams
Plain-English summary
This CVE describes a denial-of-service flaw in NASM 2.15rc0. A crafted assembly file can trigger a buffer overflow while NASM scans input, crashing the assembler or build process. Business risk is mainly disruption to build, analysis, or submission systems that process untrusted assembly files.
Executive priority
Treat this as a targeted operational resilience issue, not an enterprise-wide emergency. Prioritize teams that compile or analyze untrusted assembly files, especially automated services where crashes can interrupt customer-facing workflows or security analysis.
Technical view
The record identifies a buffer overflow in NASM's scan function in stdscan.c. The reported impact is denial of service via a crafted asm file. The source bundle does not provide CVSS, CWE, fixed version, or complete affected-version metadata beyond NASM 2.15rc0.
Likely exposure
Exposure is most likely where NASM 2.15rc0 processes externally supplied or untrusted .asm files, such as CI pipelines, code-submission platforms, malware-analysis sandboxes, or automated build services. Systems using other versions are not confirmed affected by the supplied evidence.
Exploitation context
CISA KEV status is false, and the supplied sources do not claim active exploitation. The described attack requires getting a crafted assembly file processed by the vulnerable NASM scanner. Evidence supports denial of service, not code execution.
Researcher notes
The public record is sparse: no CVSS, CWE, patch reference, or broad affected-version range is provided in the bundle. Do not generalize impact beyond NASM 2.15rc0 and denial of service unless additional vendor or maintainer evidence is reviewed.
Mitigation direction
- Identify any NASM 2.15rc0 installations in developer, CI, and analysis environments.
- Avoid processing untrusted assembly files with NASM 2.15rc0.
- Run assembly processing in constrained build or sandbox environments.
- Check NASM vendor guidance and the referenced bug for fixed-version information.
- Upgrade or replace affected NASM builds if vendor guidance confirms a safe version.
Validation and detection
- Confirm whether NASM 2.15rc0 is present on build and analysis hosts.
- Map workflows that accept third-party or user-submitted assembly files.
- Review build logs for NASM crashes during assembly-file scanning.
- Check dependency manifests and container images for bundled NASM versions.
- Monitor the CVE and NASM bug reference for remediation updates.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2020-21687 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.nasm.us/show_bug.cgi?id=3392645CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.