Security readout for executives and security teams
Plain-English summary
CVE-2020-21685 is a denial-of-service issue in NASM 2.15rc0. A specially crafted assembly file can trigger a buffer overflow while NASM processes hash lookup logic, potentially crashing the assembler. Business impact is mainly build or analysis disruption where untrusted assembly files are accepted.
Executive priority
Treat as targeted operational risk, not an emergency, unless your environment processes untrusted assembly files. Prioritize inventory and isolation over broad incident response because evidence for active exploitation is absent.
Technical view
The reported flaw is a buffer overflow in hash_findi in hashtbl.c in NASM 2.15rc0. The CVE description states remote attackers can cause denial of service via a crafted asm file. No CVSS score, CWE, fixed version, or affected CPE data is provided in the bundle.
Likely exposure
Exposure is most likely in development, CI, malware-analysis, or code-ingestion systems that run NASM 2.15rc0 against assembly files from outside trusted repositories.
Exploitation context
The bundle does not show KEV listing or active exploitation. The described attack requires NASM to process a crafted assembly file, so exposure depends on file-ingestion workflows rather than broad network reachability.
Researcher notes
Evidence is sparse: the bundle identifies NASM 2.15rc0, hash_findi in hashtbl.c, and denial of service via crafted asm input. It does not provide exploit status, patch details, CVSS, CWE, or full affected-version range.
Mitigation direction
- Inventory NASM usage and identify any 2.15rc0 installations.
- Avoid processing untrusted assembly files with affected NASM versions.
- Run assembler workloads in isolated, resource-limited build environments.
- Check NASM bug 3392644 and CVE records for vendor-confirmed fixes.
- Prefer vendor-supported NASM releases once confirmed by project guidance.
Validation and detection
- Check build images, developer systems, and CI runners for NASM 2.15rc0.
- Map workflows that accept externally supplied .asm files.
- Review recent assembler crashes or failed builds involving unusual assembly inputs.
- Confirm whether NASM project guidance names a fixed release.
- Track CVE record updates for severity, CWE, or affected-version clarification.
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-2020-21685 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=3392644CVE 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.