Security readout for executives and security teams
Plain-English summary
CVE-2018-20535 is a memory safety bug in NASM 2.14rc16. A crafted assembler/preprocessor input can trigger a use-after-free and crash the assembler, causing denial of service. Business impact is most likely disruption of build or analysis pipelines that process untrusted assembly input.
Executive priority
Treat this as a targeted build-tool resilience issue, not an emergency internet-facing risk. Prioritize if your organization compiles third-party or user-submitted assembly, operates package builders, or exposes compilation services.
Technical view
The issue is a use-after-free in asm/preproc.c, function pp_getline, in Netwide Assembler 2.14rc16. The described failure occurs during a line-number increment attempt and results in denial of service. The source bundle does not provide CVSS, CWE, affected CPEs, or confirmed fixed versions.
Likely exposure
Exposure is likely limited to environments running NASM 2.14rc16, especially CI, build farms, package builders, or research tooling that processes untrusted assembly source. Public internet exposure is unlikely unless NASM is reachable through an upload, compilation, or analysis service.
Exploitation context
The source bundle does not show CISA KEV inclusion or other evidence of active exploitation. The documented impact is denial of service, not privilege escalation or data theft. No exploit mechanics should be inferred beyond malformed input reaching NASM.
Researcher notes
Evidence is sparse: the CVE record identifies NASM 2.14rc16 and pp_getline, but lacks CVSS, CWE, CPEs, and fixed-version details. Analysis should stay constrained to denial of service unless additional vendor evidence establishes broader impact.
Mitigation direction
- Inventory NASM versions in developer workstations, CI images, and build containers.
- Prioritize replacement of NASM 2.14rc16 where untrusted input is processed.
- Check NASM Bugzilla and vendor packaging guidance for fixed or recommended versions.
- Restrict assembler jobs from accepting untrusted source without isolation.
- Run assembly processing in disposable, resource-limited build environments.
Validation and detection
- Confirm whether NASM 2.14rc16 exists in current build environments.
- Review CI and package build workflows for untrusted assembly input paths.
- Check historical build logs for unexplained NASM crashes or denial-of-service symptoms.
- Verify remediation against vendor or distribution package metadata.
- Document any remaining accepted exposure and compensating isolation controls.
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-2018-20535 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=3392530CVE reference · x_refsource_MISC
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.