Security readout for executives and security teams
Plain-English summary
CVE-2021-33459 is a crash bug in Yasm 1.3.0. A malformed NASM-style directive can cause a NULL pointer dereference in the parser. The business impact is mainly availability where Yasm processes untrusted or automated build inputs. The source bundle does not provide a vendor fix, CVSS score, or evidence of active exploitation.
Executive priority
Handle as a targeted availability risk, not an emergency, unless Yasm processes untrusted inputs in automated production or customer-facing workflows. Prioritize inventory and update decisions because fix evidence is incomplete.
Technical view
The CVE identifies a NULL pointer dereference in nasm_parser_directive() within modules/parsers/nasm/nasm-parse.c in Yasm 1.3.0. Public references indicate a parser crash condition, but the supplied sources do not define CVSS, CWE, affected CPEs, fixed versions, or complete remediation guidance.
Likely exposure
Exposure is most likely in developer workstations, CI systems, packaging pipelines, or services that invoke Yasm 1.3.0 on externally supplied or low-trust assembly files.
Exploitation context
The CVE is not listed in KEV in the supplied bundle. Public issue and gist references suggest a reproducible crash, but there is no sourced evidence here of active exploitation, privilege impact, or remote code execution.
Researcher notes
The strongest sourced facts are Yasm 1.3.0, NULL pointer dereference, nasm_parser_directive(), and the NASM parser file path. The affected range and remediation state are not established in the provided sources, so avoid broad version claims.
Mitigation direction
- Inventory systems and pipelines using Yasm 1.3.0.
- Avoid processing untrusted assembly input with affected Yasm builds.
- Check Yasm project guidance for fixes or safer versions.
- Run Yasm in constrained build environments where practical.
- Monitor vendor and distribution advisories for package updates.
Validation and detection
- Confirm installed Yasm versions across workstations and CI runners.
- Identify workflows that pass external files to Yasm.
- Review build logs for unexplained Yasm parser crashes.
- Check whether distributions have backported a relevant fix.
- Document remaining exposure where upgrades are unavailable.
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-2021-33459 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://github.com/yasm/yasm/issues/167CVE reference · x_refsource_MISC
- https://gist.github.com/Clingto/bb632c0c463f4b2c97e4f65f751c5e6dCVE 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.