Security readout for executives and security teams
Plain-English summary
CVE-2021-33454 is a crash bug in Yasm 1.3.0, an assembler used in some build toolchains. A malformed input can trigger a NULL pointer dereference. The available sources do not show data theft, code execution, or confirmed active exploitation.
Executive priority
Treat this as a targeted build-tool reliability risk, not an emergency based on current evidence. Prioritize teams that compile untrusted or third-party source with Yasm 1.3.0.
Technical view
The issue is a NULL pointer dereference in yasm_expr_get_intnum() within libyasm/expr.c in Yasm 1.3.0. Public metadata provides no CVSS, CWE, affected CPEs, or named fixed version. The practical impact evidenced by the sources is likely process crash when parsing crafted input.
Likely exposure
Exposure is most likely on developer workstations, CI runners, build containers, or packaging systems that run Yasm 1.3.0, especially where third-party or untrusted assembly source is processed.
Exploitation context
CISA KEV is false in the supplied bundle, and no cited source claims active exploitation. Public references include a GitHub issue and a gist, suggesting reproducibility information exists, but the bundle does not establish weaponized use.
Researcher notes
The CVE record is sparse: no CVSS, CWE, CPE, or fixed version is provided. Analysis should stay bounded to Yasm 1.3.0 and the NULL pointer dereference in yasm_expr_get_intnum(). Further confirmation requires upstream maintainer or package-distribution data.
Mitigation direction
- Inventory build hosts and containers for Yasm 1.3.0.
- Check upstream Yasm issue and package maintainers for patch or fixed-release guidance.
- Avoid processing untrusted assembler input with affected Yasm until vendor guidance is confirmed.
- Run affected build jobs in isolated workers with crash containment.
- Prioritize remediation where Yasm handles third-party source packages.
Validation and detection
- Confirm installed Yasm versions on developer, CI, and packaging systems.
- Review SBOMs and lockfiles for Yasm 1.3.0 references.
- Identify workflows that invoke Yasm on external or contributor-supplied inputs.
- Check build logs for unexplained Yasm crashes during assembly parsing.
- Track the upstream GitHub issue for maintainer status and fix references.
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-2021-33454 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/166CVE 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.